BOC: Microbiology, Success in CLS Ch. 6 Bacteriology (360 q.)
301. A suspension of the test organism for use in broth dilution and disk diffusion testing is adjusted to match the turbidity of a
#0.5 McFarland standard
The expected colony count in a suprapubic urine from a healthy individual is: 0 CFU/mL 100 CFU/mL 1,000 CFU/mL 100,000 CFU/mL
0 CFU/mL
334. The ability of a microorganism to deaminate phenylalanine can be assessed by inoculating a phenylalanine agar slant with the test organism. Following incubation, if the organism is positive, a green color develops with the addition of
10% feme chloride
Which of the following clean catch urine culture colony counts indicates the patient likely has a urinary tract infection? 10¹ CFU/mL 10³ CFU/mL 10⁵ CFU/mL No growth
10³ CFU/mL
How many hours after eating contaminated food do initial symptoms of staphylococcal food poisoning typically occur? 2-6 hours 12-18 hours 24-48 hours 72 hours to a week
2-6 hours
207. The finding of five to six acid-fast bacilli per field (X 800 to X 1000) in a fuchsin smear of expectorated sputum should be reported as
3+
222. Skin cultures for the recovery of Mycobacterium spp. should be incubated at
30°C Mycobacteria associated w/ these type of infections include M. ulcerans, M. marinum, and M. haemphilium.
The scolex of Taenia saginata has: 4 suckers No suckers and 14 hooklets 24 hooklets 26-28 sucking discs
4 suckers
The optimal incubator temperature for isolation of the Campylobacter jejuni/coli group is: 4°C 20°C 25°C 42°C
42°C
330. In capnophilic incubators, carbon dioxide concentrations should be maintained between
5% and 10%
Optimum growth of Campylobacter jejuni is obtained on suitable media incubated at 42°C in an atmosphere containing: 6% O₂, 10-15% CO₂, 85-90% nitrogen 10% H₂, 5% CO₂, 85% nitrogen 10% H₂, 10% CO₂, 80% nitrogen 25% O₂, 5% CO₂, 70% nitrogen
6% O₂, 10-15% CO₂, 85-90% nitrogen
A clean catch urine sample from a nursing home patient is cultured using a .001 mL loop. It grows 67 colonies of a lactose fermenter that has the following biochemical reactions: TSI: acid/acid Oxidase: negative Motility: positive Indole: negative Citrate: positive VP: positive Lysine decarboxylase: negative Ornithine decarboxylase: positive Urea: negative What should the microbiologist report? 670 CFU/mL Serratia marsecens sp 6,700 CFU/mL Providencia stuartii 67,000 CFU/mL Enterobacter cloacae 67,000 CFU/mL Klebsiella oxytoca
67,000 CFU/mL Enterobacter cloacae
311. The pH of the agar used for the Kirby-Bauer test should be
7.2-7.4
A sheep blood agar plate inoculated with 0.001 mL of urine grows 70 colonies of Staphylococcus aureus. How many colony forming units per mL of urine should be reported? 70 700 7,000 70,000
70,000
306. The minimum bactericidal concentration (MBC) of an antimicrobial agent is defined as the lowest concentration of that antimicrobial agent that kills at least
99.9%
132. Which of the following is true concerning Campylobacter jejuni?
A leading cause of bacterial diarrhea worldwide look for spreading, nonhemolytic colonies, which may be slightly pigmented "Darting" motility on wet mount
Appropriate culture requirements for a specimen from a patient suspected of having tularemia include: A media with cysteine such as buffered charcoal yeast extract agar Colistin nalidixic acid agar Mueller-Hinton agar with 5% sheep blood agar Regan-Lowe media
A media with cysteine such as buffered charcoal yeast extract agar
231. The characteristic colony morphology of Actinomyces israelii on solid agar resembles
A molar tooth Actinomyces israelii - GPB, non-spore-forming, anaerobic, slow growing and opportunistic. Colonies take 5-7 days and appear white, opaque, lobate, irregular, and shiny
115. Shigella sonnei is differentiated from other Shigella sp. by
A positive ONPG
Establishing the pathogenicity of a microorganism isolated from a childs throat and identified as Corynebacterium diphtheria would depend upon: The morphological appearance as revealed by Gram stain The type of hemolysis on blood agar A positive toxigenicity test The appearance of growht on Tinsdale tellurite agar
A positive toxigenicity test
276. Which of the following is not true of Coxiella burnetii?
A rash appears first on the extremities and then on the trunk. No rash occurs in Coxiella burnetii infections; rashes occur with rickettsial diseases.
Proper collection of a sample for recovery of Enterobius vermicularis includes collecting: A 24-hour urine collection A first morning stool collection with proper preservative A scotch tape preparation from the perianal region Peripheral blood from a finger
A scotch tape preparation from the perianal region
The optimal wound specimen for culture of anaerobic organisms should be: A swab of lesion obtained before administration of antibiotics A swab of lesion obtained after administration of antibiotics A syringe filled with pus, obtained before administration of antibiotics A syringe filled with pus, obtained after administration of antibiotics
A syringe filled with pus, obtained before administration of antibiotics
An AFB broth culture is positive for acid-fast bacilli at 1 week while the agar slant shows no growth. The most likely explanation for this is: The organism is a contaminant AFB grow more rapidly in liquid media PANTA was added to the broth The agar slant was incubated at 5% CO₂
AFB grow more rapidly in liquid media
The Gram stain from a blood culture shows gram-positive cocci in chains. No growth occurs on blood agar plates incubated both aerobically and anaerobically. Additional testing should be done to detect the presence of: Staphylococcus saprophyticus Aerococcus urinae Abiotrophia defectiva Streptococcus pneumoniae
Abiotrophia defectiva
30. Enterococcus faecium is characteristically
Able to grow in the presence of high concentrations of salt
145. Acinetobacter baumannii is characteristically
Able to grow on MacConkey agar -oxidase = -nonmotile -resistant to penicillin
150. Kingella denitrificans can be differentiated from Neisseria gonorrhoeae because it is
Able to reduce nitrates
Acceptable specimens for culture of anaerobic bacteria that cause disease include: Abscesses Gingival swabs Skin swabs Vaginal swab
Abscesses
200. Eikenella corrodens is an opportunistic pathogen, but it is most noted for causing
Abscesses of the oral cavity
235. Color Plate 29 shows the filamentous gram-positive rod recovered from an aspirate of a closed chest abscess. It grew only under anaerobic conditions and was not acid-fast. What is the most likely presumptive identification of the isolate seen?
Actinomyces israelii -closed chest abscess characteristic of human actinomycosis -anaerobic, G+ non-spore-forming bacillus -differentiate from Nocardia because Actinomyces is not acid fast -pus shows "sulfur granules" or solid yellow particles made of masses of bacteria
Children who have infections with beta-hemolytic streptococci can develop: Acute pyelonephritis Acute glomerulonephritis Chronic glomerulonephritis Nephrosis
Acute glomerulonephritis
Colds and other acute respiratory diseases are most often associated with: Epstien-Barr virus Adenovirus Coxsackie B Reovirus
Adenovirus
105. Which of the following is true of Neisseria gonorrhoeae?
Adversly affected by fatty acids in clinical specimens
102. Identify the fermentative agent that may infect reptiles and fish as well as humans when they are exposed to contaminated soil or water.
Aeromonas
73. A fermentative gram-negative bacillus that is oxidase positive, motile, and grows well on MacConkey agar is
Aeromonas hydrophila
While swimming in a lake near his home, a young boy cut his foot, and an infection developed. The culture grew a nonfastidious gram-negative, oxidase positive, beta-hemolytic, motile bacilli that produced deoxyribonuclease. The most likely identification is: Enterobacter cloacae Serratia marcescens Aeromonas hydrophila Escherichia coli
Aeromonas hydrophila
340. Methyl red-Voges Proskauer (MRVP) broth is inoculated and incubated for 48 hours. What two reagents must be added to determine if the bacterium is VP positive?
Alpha-naphthol and 40% KOH
337. In the nitrate test, reduction is demonstrated by the development of a red color, following the addition of
Alpha-naphthylamine and sulfanilic acid
254. Which of the following statements is true regarding Clostridium perfringens?
Alpha-toxin is produced by all strains. -Clostridium perfringens spores are oval and central and rarely seen in lab cultures. -Five types (A-E)
149. Which of the following is not characteristic of Haemophilus influenzae biogroup aegyptius?
Aminolevulinic acid positive H. influenzae biogroup aegypticus causes conjunctivitis and Brazilian purpuric fever. Requires both X and V factors. ALA =. indole =, urease +, ornithine decarboxylase =
264. Which of the following is not true of Bacteroides fragilis?
Among the most antimicrobial sensitive anaerobic bacteria Its the MOST RESISTANT
338. The Moeller test for the detection of decarboxylase activity is dependent upon
An alkaline pH shift in the medium
The diagnosis of Neisseria gonorrhoeae in females is best made from: Clinical history An endocervical culture A Gram stain of cervical secretions Examination for clue cells
An endocervical culture
The etiologic agent of botulism is: Highly motile Non-spore-forming Clostridium perfringens An exotoxin producer
An exotoxin producer
A sputum specimen received at 8 am for an AFB smear reveals acid-fast bacilli. An additional sputum is submitted that afternoon. This specimen was concentrated by the NALC-sodium hydroxide method and inoculated on 2 Lowenstein-Jensen slants and held for 8 weeks at 35°C in 5-10% CO₂. No growth occurs. The best explanation is that: The hypochlorite technique was not used An improper specimen was submitted for culture Improper media was used for culture Cultures were held for an insufficient period of time
An improper specimen was submitted for culture
32. A Gram stain of a sputum specimen from a patient with a suspected case of lobar pneumonia reveals many white blood cells and many gram-positive cocci, which are primarily diplococci. Which of the following statements would be appropriate, given these findings?
An optochin test should be performed on the culture isolate. -Lobar pneumonia caused mainly by Strep pneumoniae
232. What is the predominant indigenous flora of the colon?
Anaerobic, gram-negative, non-spore-forming bacteria Bacteroides fragilis
Gram stain from a thigh wound showed many gram-positive spore-forming bacilli. The specimen was blaced on brain heart infusion blood agar and incubated aerobically at 35°c for 3 days. At the end of that time, the plates showed no growth. The most likely explanation is that some of the specimen should have been incubated: On chocolate agar For 5 days Under 5% CO₂ Anaerobically
Anaerobically
351. Gram-positive rods were recovered from the chest fluid drawn from a teenager with right lower lobe pneumonia who lived on a dairy farm. At 24 hours, pinpoint colonies grew on sheep blood agar that showed faint zones of beta-hemolysis. The isolate was catalase negative and demonstrated a positive CAMP test. Which of the following is the most likely etiologic agent in this case?
Arcanobacterium pyogenes
237. The diagnosis of pseudomembranous colitis (Clostridium difficile associated disease) is often made by
Assays to detect toxin in stool -fastest way to diagnose it is to detect toxins A and/or B in stool specimens. Cycloserine-cefoxitin-fructose agar (CCFA) is the recommended isolation media for C. diff.
90. An important characteristic of Neisseria gonorrhoeae or the infection it produces is
Asymptomatic infections are common in females.
220. Which of the following is a fluorescent stain for mycobacteria?
Auromine-rhodamine - appear bright yellow against a black background
275. Chlamydophila (Chlamydia) psittaci infections in humans most commonly result after exposure to infected
Avians
39. Which of the following species of Bacillus is nonmotile?
B. anthracis
14. Which of the following is the most commonly isolated species of Bacillus in opportunistic infections such as bacteremia, post-traumatic infections of the eye, and endocarditis?
B. cereus -virulence factors: enterotoxin, pyogenic toxin.
318. The supervisor of a microbiology laboratory has been asked to begin performing in vitro antimicrobial susceptibility testing of Mycobacterium tuberculosis because of an increase in the reported resistance in his community. Which of the following methods would be appropriate for this testing?
BACTEC method
Fluid from a cutaneous black lesion was submitted for routine bacterial culture. After 18 hours of incubation at 35°C there was no growth on MacConkey agar, but 3+ growth on sheep blood agar. The colonies were nonhemolytic, nonmotile, 4-5 mm in diameter and off-white with a ground glass appearance. Each colony had an irregular edge with comma-shaped outgrowths that stood up like "beaten egg whites" when gently lifted with an inuculating needle. A Gram stain of a typical colony showed large, gram-positive rectangular bacilli. The organism is most likely: Clostridium perfringens Aeromonas hydrophila Bacillus anthracis Mycobacterium marinum
Bacillus anthracis
63. The causative agent of "malignant pustule" is
Bacillus anthracis Malignant pustules seen in cutaneous anthrax.
53. The description of "Medusa head" colonies on solid agar is most characteristic of
Bacillus anthracis -large, spore-forming, GPB grows in long chains
Which organism commonly causes food poisoning by consumption of foods containing excessive populations of organisms or performed enterotoxin? Salmonella enteritidis Shigella sonnei Bacillus cereus Escherichia coli
Bacillus cereus
In a quality control procedure on a new batch of Mueller-Hinton plates using a stock culture of Staphylococcus aureus (ATCC 25923), all the disk zone sizes are too small. The most likely reason for this is that the: Mueller-Hinton plates were poured too thin Potency of the antibiotic disks is too high Bacterial suspension was not diluted to the proper concentration Disks should have been set up on mannitol salt
Bacterial suspension was not diluted to the proper concentration
Which of the following genera include anaerobic gram-negative nonsporulating bacilli? Brucella Pasteurella Actinomyces Bacteroides
Bacteroides
236. Growth on kanamycin-vancomycin laked blood agar incubated anaerobically is primarily used for
Bacteroides fragilis -kanamycin-vancomycin laked blood (KVLB) agar is selective for Bacteroides and Prevotella -Bacteroides is resistant to both kanamycin and vancomycin -Fusobacterium is resistant only to vancomycin.
233. Obligately anaerobic, gram-negative bacilli, recovered from an abdominal wound, were found to be resistant to penicillin. Growth of this organism was not inhibited by bile. What is the most likely identification of this isolate?
Bacteroides fragilis group -most commonly isolated anaerobe -part of the normal fecal flora
Which of the following pair sof organisms usually grown on kanamycin, vancomycin, lake blood agar? Bacteroides and Prevotella Mobiluncus and Gardnerella Porphyromonas and Enterococcus Veillonella and Capnocytophaga
Bacteroids and Prevotella
170. The causative agent of the septicemic, hemolytic disease known as Oroya fever is
Bartonella bacilliformis causes Oroya fever and verruga peruana. pleomorphic, GNR, intracellular parasite
An aspirate of a deep wound was plated on blood agar plates aerobically and anaerobically. At 24 hours there was growth on the anaerobic plate only. The next step in the evaluation of this culture is to: Reincubate for another 24 hours Begin organism identification Issue the final report Set up a Bauer-Kirby sensitivity
Begin organism identification
The ONPG test allows organisms to be classified as a lactose fermenter by testing for which of the following? Permease Beta-galactosidase Beta-lactamase Phosphatase
Beta-galactosidase
120. Which of the following reactions is typical for Escherichia coli?
Beta-hemolytic on sheep blood agar Yellow colonies on XLD agar Pink colonies on MacConkey agar Orange colonies on Hektoen enteric agar
A penicillin-resistant Neisseria gonorrhoeae produces: Alpha-hemolysin Beta-lactamase Enterotoxin Coagulase
Beta-lactamase
Haemophilus influenzae becomes resistant to ampicillin when the organism produces a(n): Capsule of polysaccharide material Affinity for the beta-lactam ring of the ampicillin Porphobilinogen Beta-lactamase enzyme
Beta-lactamase enzyme
319. Clavulanic acid is classified as a
Beta-lactamase inhibitor
Gram-positive cocci in chans are seen on a Gram stain from a blood culture. The organism grows as a beta-hemolytic colony. Further tests that could be performed include: Bile, esculin, PYR, bacitracin, and hippurate Catalase and coagulase Oxidase and deoxyribonuclease Voges-Proskauer and methl red
Bile esculin, PYR, bacitracin, and hippurate
190. The selective nature of Hektoen enteric agar is due to the inclusion of which one of the following?
Bile salts
Streptococcus pneumoniae can be differentiated best from the viridans group of streptococci by: Gram stain The type of hemolysis Colonial morphology Bile solubility
Bile solubility
Viridans streptococci can be differentiated from Streptococcus pneumoniae by: Alpha hemolysis Morphology Catalase reaction Bile solubility
Bile solubility
28. Which one of the following is not appropriate when describing Streptococcus pneumoniae?
Bile-resistant
343. Which of the following statements does not apply to the acridine orange stain?
Binds to the teichoic acid of the cell wall
Psittacosis is transmissible to man via contact with: Insects Birds Cattle Dogs
Birds
16. On Tinsdale agar, colonies of Corynebacterium diphtheriae are characterized by the observance of
Black colonies on the culture medium surrounded by brown halos -inhibits indigenous respiratory flora
66. In suspected cases of brucellosis, the optimal specimen to be collected for the isolation of the etiologic agent is
Blood -Brucellae: small, nonmotile, G= cb, facultative intracellular parasites.
Propionibacterium acnes is most often associated with: Normal oral flora Post-antibiotic diarrhea Tooth decay Blood culture contamination
Blood culture contamination
348. A 36-year-old man was seen in the emergency department. He complained of fever and headache. He had returned 1 week previously from a 6-week visit to a village in India. Among the differential diagnoses was typhoid fever. What is the most critical laboratory test necessary to establish or eliminate the diagnosis?
Blood cultures
329. Which of the following is not a correct statement regarding blood cultures?
Blood drawn for culture may be allowed to clot
A gram-negative bacillus has been isolated from feces, and the confirmed biochemical reactions fit those of Shigella. The organism does not agglutinate in Shigella antisera. what should be done next? Test the organism with a new lot of antisera Test with Vi antigen Repeat the biochemical tests Boil the organism and retest with the antisera
Boil the organism and restest with the antisera
Which of the following specimens is considered to be the most sensitive for the recovery of Brucella in cases of chronic infection? Blood Urine Bone marrow Lymph node
Bone marrow
100. In suspected cases of brucellosis, what is the most sensitive specimen to submit for culture?
Bone marrow Brucella spp. are fastidious, G= cb. Blood and bone marrow acceptable.
323. Chloramphenicol is an important antimicrobial agent for the treatment of meningitis as well as several other serious infections. Unfortunately, chloramphenicol exhibits significant complications that limit its clinical usefulness. These effects include
Bone marrow suppression and aplastic anemia
181. Which of the following is an occasional cause of respiratory tract infections and is rapidly urea positive?
Bordetella bronchiseptica
184. Colonies that are said to resemble "droplets of mercury" are characteristic of
Bordetella pertussis
89. The etiologic agent of whooping cough is
Bordetella pertussis -minute, encapsulated, nonmotile, G= pleomorphic bacillus. Regan-Lowe medium.
Relapsing fever in humans is caused by: Borrelia recurrentis Brucella abortus Leptospira interrogans Spirillum minus
Borrelia recurrentis
248. Which of the following is the most potent bacterial exotoxin known?
Botulinum toxin
227. Which of the following is not considered a zoonotic disease?
Botulism
Which species of Mycobacterium includes a BCG stain used for vaccination against tuberculosis? Tuberculosis Bovis Kansasii Fortuitum/chelonae complex
Bovis
287. The mild type of typhus fever that is caused by recrudescence of an initial attack of epidemic typhus is known as
Brill-Zinsser disease (latent form of typhus caused by Ricketssia prowazekii)
141. Which of the following is the optimal clinical specimen for the recovery of Legionella pneumophila ?
Bronchial washings
158. Blood cultures are recommended for the recovery of which of the following microorganisms?
Brucella canis
187. Milk has classically been the primary food associated with the transmission of some diseases, especially for those diseases of cattle transmissible to humans, such as
Brucellosis
93. Which of the following nonfermenters is rarely isolated in the U.S.?
Burkholderia mallei
76. The causative agent of melioidosis is
Burkholderia pseudomallei
199. Besides Pseudomonas aeruginosa, which of the following is an important cause of lower respiratory tract infections in patients with cystic fibrosis?
Burkholdia cepacia Both P. aeruginosa and B. cepacia are oxidase + and will grow on MAC.
A 4-year-old is admitted with symptoms of meningitis, and a Gram stain of the cerebrospinal fluid reveals small, pleomorphic, gram-negative coccobacilli. After 24 hours incubation at 35°C, small, moist, gray colonies, which are oxidase variable, are found on the chocolate agar plate only. Which of the following biochemical data would be consistent with this isolate? A CTA dextrose: positive CTA maltose: positive ONPG: negative B Sodium hippurate hydrolysis: positive A disc: negative CAMP test: positive C X factor: no growth V factor: no growth XV factor: growth Horse blood: no hemolysis D Catalase: positive Esculin hydrolysis: positive Methyl red: positive "umbrell" motility at room temperature
C
114. The species of Campylobacter noted to produce septicemia, septic arthritis, meningitis, jaundice with hepatomegaly, and thrombophlebitis in debilitated patients is
C. fetus
249. Which Clostridium sp. is most commonly recovered from cases of gas gangrene?
C. perfringens
241. Which of the following clostridia has a terminal spore that causes the cell to swell?
C. tetani -spore is located terminally and is larger than the sporangium. -resemble a drumstick or tennis racket on Gram stain.
251. Which of the following statements is not true of clostridia?
C.tetani spores will form in the presence of oxygen; therefore, anaerobiosis in a wound is not required to cause tetanus.
An isolate of an unknown beta-hemolytic Streptococcus is streaked perpendicular to a streak of beta-lysin-producing Staphylococcus aureus. After incubation a zone of arrowhead hemolysis is noted at the interface of the 2 streaks. What is the name of the test and the presumptive identification of the unknown Streptococcus? Hippurate hydrolysis and S agalactiae CAMP test and S pyogenes Hippurate hydrolysis and S pyogenes CAMP test and S agalactiae
CAMP test and S agalactiae
A stool sample is sent to the laboratory for culture to rule out Clostridium difficile. What media should the microbiologist use and what is the appearnace of the organisms on this media? BBE: colonies turn black Brucella agar: red pigmented colonies CCFA: yellow, ground glass colonies CNA: double zone hemolytic colonies
CCFA: yellow, ground glass colonies
A diabetic foot swab from a 82-year-old woman with recurrent infections is submitted for culture. The Gram stain reveals: Many neutrophils, no squamous epithelial cells Many gram-negative bacilli Many gram-positive cocci in chains The physician requests that all pathogens be worked up. In addition to the sheep blood and MacConkey agar plates routinely used for wound cultures, the technologists might also process a(n): CNA agar plate Chocolate agar plate XLD agar plate Chopped meat glucose
CNA agar plate
A smear of skin tissue reveals fluorescent septate hyphae. The smear was prepared using: Acridine orange Calcofluor white Auramine rhodamine Periodic acid-Schiff
Calcofluor white
Which of the following must be incubated in a microaerophilic environment for optimal recovery of the organism? Campylobacter jejuni Escherichia coli Pseudomonas aeruginosa Proteus mirabilis
Campylobacter jejuni
165. On Gram stain, a morphology that resembles "seagull wings" is most characteristic of
Campylobacter jejuni GNB, "darting" motility on wet mount
The formation of germ tubes presumptively identifies: Candida tropicalis Candida parapsilosis Candida glabrata Candida albicans
Candida albicans
Which of the following statements concerning the germ tube test is true? Using a heavy inoculum enhances the rapid production of germ tubes Germ tubes should be read after 2 hours incubation at 25°C Candida albicans and Candida tropicalis can be used as positive and negative controls, respectively Serum will be stable for 1 year if stored at 4°C to use
Candida albicans and Candida tropicalis can be used as positive and negative controls, respectively
The disease-producing capacity of Mycobacterium tuberculosis depends primarily upon: Production of exotoxin Production of endotoxin Capacity to withstand intracellular digestion by macrophages Lack of susceptibility to the myeloperoxidase system
Capacity to withstand intracellular digestion by macrophages
80. A fastidious gram-negative bacillus was isolated from a case of periodontal disease, which upon darkfield examination was noted to have gliding motility. The most likely identification of this etiologic agent would be
Capnocytophaga - fermentative G=
A yeast isolate from a CSF specimen produced the following results: India ink: no encapsulated yeast cells Cryptococcal antigen: negative Urea: negative Germ tube: negative What should the technologist do next to identify this organism? Inoculate bird seed agar Ascospore stain Cycloheximide susceptibility Carbohydrate assimilation
Carbohydrate assimilation
An organism previously thought to be nonpathogenic, Moraxella catarrhalis, is known to be associated with opportunistic respiratory infection and nonsocomial examination. Characteristic identification criteria include: Oxidase negative Carbohydrates negative (asaccharolytic) Beta-lactamase negative Gram-negative bacilli
Carbohydrates negative (asaccharolytic)
Tubercle bacilli are specifically stained by: Crystal violet 1% acid fuchsin Methylene blue Carbol fuchsin
Carbol fuchsin
The primary isolation of Neisseria gonorrhoeae requires: Anaerobic conditions Starch media Carbon dioxide Blood agar
Carbon dioxide
22. Streptococci are unable to synthesize the enzyme
Catalase
36. Which of the following is not characteristic of Listeria monocytogenes?
Catalase negative
Gram stain examination from a blood culture bottle shows dark blue, spherical organisms in clusters. Grown on sheep blood agar shows small, round, pale yellow colonies. Further tests should include: Catalase production and coagulase test Bacitracin susceptibility and serological typing Oxidase and deoxyribonuclease reactions Voges-Proskauer and methyl red reactions
Catalase production and coagulase test
The most common cause for failure of a GasPak anaerobic jar to establish an adequate environment for anaerobic incubation is: The failure of the oxidation-reduction potential indicator system due to deterioration of methylene blue The failure of the packet to generate adequate H₂ and/or CO₂ Condensation of water on the inner surface of the jar Catalysts that have become inactivated after repeated use
Catalysts that have become inactivated after repeated use
In the Kirby-Bauer disc diffusion susceptibility test, which variable is critical when testing Pseudomonas species for antibiotic susceptibility to aminoglycosides? Incubation temperature Duration of incubation Cation content of media Depth of agar
Cation content of media
The enterotoxin produced by certain strains of hemolytic, coagulase positive Staphylococcus aureus: Is destroyed by boiling for 15-30 minutes Is identical to the dermonecrotic toxin Causes one type of bacterial food poisoning Is highly antigenic
Causes one type of bacterial food poisoning
189. Which of the following is not appropriate for the cultivation of Neisseria gonorrheae?
Cefsulodin-irgasan-novobiocin agar
Which of the following combinations is useful for confirming the presence of extended spectrum beta-lactamase in E coli? Ampicillin + cefepime Cefoxitin + penicillin Ceftazidime + clavulanic acid Cefpodoxime + cefotaxime
Ceftazidime + clavulanic acid
314. The extended-spectrum beta-lactamase confer resistance to
Ceftriaxone
The best method to demonstrate the ova of Enterobius vermicularis is: Acid-ether concentration Cellophane tape preparation Formalin-ether concentration Zinc sulfate flotation
Cellophane tape preparation
First generation cephalosporins can be adequately represented by: Cefotetan Ceftriaxone Cephalothin Cefoxitin
Cephalothin
155. Haemophilus ducreyi is the causative agent of
Chancroid
85. The sexually acquired disease characterized by genital ulcers and tender inguinal lymphadenopathy, which is caused by a small, gram-negative bacillus, is known as
Chancroid caused by Haemophilus ducreyi, a small G= cb.
Media used to support growth of Legionella pneumophila should contain which of the following additives? X and V factors Hemin and Vitamin K Charcoal and yeast extract Dextrose and laked blood
Charcoal and yeast extract
278. Corneal scrapings are collected and examined microscopically using a direct fluorescent test to detect inclusion bodies for the diagnosis of infection caused by
Chlamydia trachomatis
272. Which one of the following microorganisms cannot be cultivated on artificial cell-free media?
Chlamydia trachomatis Chlamydia and Chlamydiophila are obligate intracellular parasites
223. Which of the following media would not be routinely used to culture Mycobacterium spp.?
Chocolate agar
Cerebrospinal fluid from a febrile 25-year-old man with possible meningitis is rushed to the laboratory for a stat Gram stain and culture. While performing the Gram stain, the technologist accidentally spills most of the specimen. The smear shows many neutrophils and no microorganisms. Since there is only enough CSF to inoculate one plate, the technologist should use a: Blood agar plate Chopped meat glucose Chocolate agar plate Thayer-Martin plate
Chocolate agar plate
Proper media for culture of a urethral discharge from a man: Sheep blood and phenyl ethyl alcohol agars Eosin-methylene blue and sheep blood agars Thioglycollate broth and chocolate agar Chocolate and modified Thayer-Martin agars
Chocolate and modified Thayer-Martin agars
174. Violet-colored colonies are typically produced by
Chromobacterium violaceum motile, GNB, catalase and oxidase +
71. An environmental sampling study of respiratory therapy equipment produced cultures of a yellow, nonfermentative (at 48 hours), gram-negative bacillus from several of the nebulizers, which would most likely be species of
Chryseobacterium
252. Gram-positive bacilli with central spores are seen in the direct Gram stain of a tissue biopsy. After 24 hours of incuba- tion, no growth is seen on the sheep blood agar plate incubated aerobically and the chocolate agar plate incubated in increased CO2. Which of the following is the likely cause of the infection?
Clostridium
226. The potentially lethal intoxication type of food poisoning often associated with improperly canned food is caused by
Clostridium botulinum
269. Which of the following is an important cause of food poisoning?
Clostridium perfringens
An anaerobic, spore-forming, nonmotile, gram-positive bacillus isolated from a foot wound is most likely: Actinomyces israelii Clostridium perfringens Bacillus subtilis Eubacterium lentum
Clostridium perfringens
The reverse CAMP test, lecithinase production, double zone hemolysis, and Gram stain morphology are all useful criteria in the identification of: Clostridium perfringens Streptococcus agalactiae Propionibacterium acnes Bacillus anthracis
Clostridium perfringens
228. An anaerobically incubated blood agar plate shows colonies surrounded by an inner zone of complete red cell lysis and an outer zone of incomplete cell lysis (double zone of hemolysis). The most likely presumptive identification of this isolate would be
Clostridium perfringens - anaerobic, spore-forming, GPB. Identify on egg yolk agar plate to detect lecithinase production.
247. Septicemia caused by which of the following is generally associated with an underlying malignancy?
Clostridium septicum
An anaerobic gram-positive bacilli with subterminal spores was isolated from a peritoneal abscess. The most likely identification of this organism is: Bacillus cereus Clostridium septicum Eubacterium lentum Bifidobacterium dentium
Clostridium septicum
A strict anaerobe that produces terminal spores is: Clostridium tetani Crynebacterium diphtheriae Bacillus anthracis Propionibacterium acnes
Clostridium tetani
A reliable test for distinguishing Staphylococcus aureus from other staphylococci is: Oxidase Coagulase Catalase Optochin susceptibility
Coagulase
The most critical distinction between Staphylococcus aureus and other Staphylococcus is: Phosphatase reaction DNA production Coagulase production Hemolysis
Coagulase production
Lab workers should always work under a biological safety hood when working with cultures of: Streptococcus pyogenes Staphylococcus aureus Candida albicans Coccidioides immitis
Coccidioides immitis
341. Which of the following is not true of blood cultures for the recovery of bacteria?
Collect 5 mL of blood for optimal recovery of pathogen 10-20 mL recommended
Which selective medium is used for the isolation of gram-positive microorganisms? Columbia CNA with 5% sheep blood Trypticase soy agar with 5% sheep blood Eosin methylene blue Modified Thayer-Martin
Columbia CNA with 5% sheep blood
A Gram stain from a swab of a hand wound reveals: Moderate neutrophils No squamous epithelial cells Moderate gram-positive cocci in chains Moderate large gram-negative bacilli Select the appropriate media that will selectively isolate each organism. KV-laked agar, Thayer-Martin Sheep blood, MacConkey Columbia CNA, chocolate Columbia CNA, MacConkey
Columbia CNA, MacConkey
111. Which of the the following does not describe Acinetobacter sp.?
Commonly susceptible to most antimicrobials
15. Loeffler's serum medium is recommended for the cultivation of
Corynebacterium diphtheriae
2. The organism associated with a disease characterized by the presence of a pseudomembrane in the throat and the production of an exotoxin that is absorbed into the bloodstream with a lethal effect is
Corynebacterium diphtheriae
45. Cystine-tellurite blood agar plates are recommended for the isolation of
Corynebacterium diphtheriae -tinsdale medium containing tellurite causes C. diphtheriae colonies to appear dark-brown to black
59. Tellurite reduction is used for the presumptive identification of
Corynebacterium diphtheriae - blak/brown colonies on Tinsdale medium
48. An aerobic gram-positive rod known to cause bacteremia in hospitalized immunocompromised patients is
Corynebacterium jeikeium
47. Pleomorphic gram-positive bacilli in a Gram stain best describes
Corynebacterium pseudodiphtheriticum -all Corynebacterium are G+, non-spore-forming bacilli that form CHINESE CHARACTERS OR PALLISADES (pleomorphic club shaped appearance)
The most sensitive test for the initial diagnosis of cryptococal disease is: India ink Gram stain Cryptococcal antigen Giemsa stain
Cryptococcal antigen
An HIV-positive patient began to show signs of meningitis. A spinal fluid was collected and cultured for bacteria and fungus. A budding, encapsulated yeast was recovered. Which organism is consistent with this information? Cryptococcus neoformans Aspergillus fumigatus Microsporum audouinii Sporothrix schenckii
Cryptococcus neoformans
An organism that demonstrates budding yeast cells with wide capsules in an India ink preparation of spinal fluid is probably: Cryptococcus neoformans Histoplasma capsulatum Blastomyces dermatitidis Candida albicans
Cryptococcus neoformans
Which of the following procedures should be performed to confirm that an unknown mold is one of the pathogenic dimorphic fungi: Animal inoculation Culture conversion to yeast form Demonstration of sexual and asexual reproduction Serological studies
Culture conversion to yeast form
A laboratory aid receives a bronchoscopy sample with the request for culture of Legionella. The assistant asks a microbiologist for direction on plating protocol. The correct response from the microbiologist is: Culture on thiosulfate citrate bile salt media Incubate the culture media anaerobically Reject the specimen and request a sputum sample Culture on buffered charcoal yeast extract agar with antibiotics
Culture on buffered charcoal yeast extract agar with antibiotics
Serum samples collected from a patient with pneumonia demonstrate a rising antibody titer to Legionella. A bronchoalveolar lavage (BAL) specimen from this patient had a positive antigen test for Legionella but no organisms were recovered on buffered charcoal yeast extract medium after 2 days of incubation. The best explanation is that the: Antibody titer represents an earlier infection Positive antigen test is a false positive Specimen was cultured on the wrong media Culture was not incubated long enough
Culture was not incubated long enough
A first morning sputum is received for culture of mycobacteria. It is digested and concentrated by the N-acetyl-L-cysteine alkali method. Two Lowenstein-Jensen slants are incubated in the dark at 35°C with 5-10% CO₂. The smears reveal acid-fast bacilli, and after 7 days no growth appears on the slants. The best explanation is: Improper specimen submitted Incorrect concentration procedure Exposure to CO₂ prevents growth Cultures held for insufficient length of time
Cultures held for insufficient length of time
292. During the first week of leptospirosis, the most reliable way to detect the presence of the causative agent is by the direct
Culturing of blood Media of choice: Fletcher semisolid and Stuart liquid medium
An antibiotic used to suppress or kill contaminating fungi in media is: Penicillin Cycloheximide Streptomycin Amphotericin B
Cycloheximide
The recovery of some Cryptococcus species may be compromised if the isolation media contains: Cycloheximide Gentamicin Chloramphenicol Penicillin
Cycloheximide
The best medium for culture of Francisella tularensis is: Bordet-Gengou medium Cystine glucose blood agar Loeffler medium Charcoal selective medium
Cystine glucose blood agar
69. Colonies of Neisseria sp. turn color when a redox reagent is applied. The color change is indicative of the activity of the bacterial enzyme
Cytochrome oxidase
258. Which of the following tests is most appropriate for the identification of Clostridium difficile?
Cytotoxin assay
113. An unheated suspension of Salmonella Typhi typically produces agglutination of Vi antisera. After heating the same suspension, agglutination will occur in which grouping sera?
D
Differentiation of Mycobacterium avium from Mycobacterium intracellulare can be accomplished by: Nitrate reduction test Tween hydrolysis test Resistance to 10 µg thiophene-2-carboxylic acid hydrazide (TCH) DNA probe
DNA probe
281. What is the reference method for detection of Chlamydia trachomatis in cases of sexually transmitted disease?
DNA-amplification techniques
A first morning sputum specimen is received for acid-fast culture. The specimen is centrifuged, and the sediment is inoculated on 2 Lowenstein-Jensen slants, which are incubated at 35°C in 5-10% CO₂. After 1 week, the slants show abundant growth over the entire surface. Stains reveal gram-negative bacilli. To avoid this problem: Utilize a medium that inhibits bacterial growth Add sodium hypochlorite to the sediment before inoculation Incubate the tubes at room temperature to retard bacterial growth Decontaminate the specimen with sodium hydroxide
Decontaminate the specimen with sodium hydroxide
In disk diffusion susceptibility testing, as an antimicrobial agent diffuses away from the disk, the concentration of antibiotic is: Increased Decreased Unchanged Inoculum dependent
Decreased
The most meaningful laboratory procedure in confirming the diagnosis of clinical botulism is: Demonstration of toxin in the patients serum Recovery of Clostridium botulinum from suspected food Recovery of Clostridium botulinum from the patients stool Gram stain of suspected food for gram-positive, sporulating bacilli
Demonstration of toxin in the patients serum
In a suspected case of Hansen disease (leprosy), a presumptive diagnosis is established by: Isolation of organisms on Lowenstein-Jensen medium Detection of weakly acid-fast bacilli in infected tissue Isolation of organisms in a cell culture Detection of niacin production by the isolated medium
Detection of weakly acid-fast bacilli in infected tissue
A medium that aids in the presumptive identification of organisms based on their appearance on the medium is called: Enriched Selective Differential Specialized
Differential
194. Which of the following is not true about the laboratory diagnosis of pertussis?
Direct fluorescent antibody) DFA test results are definitive and do not need to be confirmed by culture.
Which of the following methods is inadequate for the detection of vancomycin-intermediate S aureus? Broth macrodilution Agar dilution Gradient diffusion Disk diffusion
Disk diffusion
A beta-hemolytic, catalase-positive, gram-positive coccus is coagulase negative by the slide coagulase test. Which of the following is the most appropriate action in identification of this organism? Report a coagulase-negative Staphylococcus Report a coagulase-negative Staphylococcus aureus Reconfirm the hemolytic reaction on a fresh 24-hour culture Do a tube coagulase test to confirm the slide test
Do a tube coagulase test to confirm the slide test
8. Nocardia asteroides infections in humans characteristically produce
Draining cutaneous sinuses -Nocardia asteroides are soil saprophytes; causes disease either by inhalation or through skin abrasions. -partially acid-fast, gram-positive, branching filamentous or coccoid organism.
78. A culture of a decubitus ulcer grew a gram-negative facultative bacillus. On TSI it produced an acid slant, acid butt, and gas. Test reactions in other media were as follows: citrate = indole + urease = ONPG + Voges-Proskauer = The organism was identified as
E. coli
101. Hemolytic uremic syndrome is a complication after infection with
E. coli O157:H7
143. Production of a yellow pigment is characteristic of which of the following Enterobacter sp.?
E. sakazakii
225. Which of the following is not true of Mycobacterium leprae?
Easily transmitted from person to person Mycobacterium leprae: cannot be grown on artificial media, optimal temperature <37°C so infections occur in the extremities on the skin. Not highly contagious.
Which type of microscope would be MOST useful in examining viruses and the structure of microbial cells? Electron Phase-contrast Dark-field Bright-field
Electron
17. Precipitates of diphtheria toxin and antitoxin formed in agar gels are an in vitro means for detecting toxigenic strains of Corynebacterium diphtheriae. The name of this test procedure is the
Elek test
Which of the following is the MOST appropriate specimen source and primary media battery? Endocervical-chocolate, Martin Lewis Sputum-sheep blood, Thayer-Martin, KV-laked blood CSF-Columbia CNA, MacConkey Urine-sheep blood, chocolate, Columbia CNA
Endocervical-chocolate, Martin Lewis
37. Which of the following is not associated with Staphylococcus aureus?
Endotoxin production
A patient is suspected of having amebic dysentery. Upon microscopic examination of a fresh fecal specimen for ova and parasites, the following data were obtained: A trophozoite of 25 µm Progressive, unidirectional crawl Evenly distributed peripheral chromatin Finely granular cytoplasm This information probably indicates: Entamoeba coli Entamoeba histolytica Endolimax nana Iodamoeba butchlii
Entamoeba histolytica
116. A positive Voges-Proskauer reaction is characteristic of
Enterobacter aerogenes Generally VP negative - most common isolates from the genera Providencia, Escherichia, Salmonella, and Proteus Generally VP positive - most members of Klebsiella, Enterobacter, and Serratia Enterobacteriaceae that are VP + are usually MR =
151. Plesiomonas was recently moved to which family?
Enterobacteriaceae Plesiomonas shigelloides is the only species in the genus.
It is important to differentiate between Enterococcus and group D streptococci because: Viridans streptococci are often confused with enterococci Several enterococi cause severe puerperal sepsis Group D streptococci are avirulent Enterococci often show more antibiotic resistance than group D streptococci
Enterococci often show more antibiotic resistance that group D streptococci
1. A test for the hydrolysis of esculin in the presence of bile is especially useful in identifying species of the genus
Enterococcus
Which of the following may be used as a positive quality control organism for the bile esculin test? Staphylococcus epidermidis Staphylococcus aureus Streptococcus pyogenes Enterococcus faecalis
Enterococcus faecalis
65. A catalase-negative gram-positive coccus is isolated from a urine sample of a hospitalized patient. The bacterium produced a black pigment on bile-esculin agar and formed acid from glucose in the presence of 6.5% NaCl. What is the most likely identification of this bacterium?
Enterococcus faecalis E. faecalis and E. faecium grow in the presence of bile, hydrolyze esculin, and produce acid from glucose in the high salt concentration.
3. Enterotoxin produced by Staphylococcus aureus is responsible for causing
Enterocolitis
25. The production of H2S is one characteristic used to differentiate which of the aerobic gram-positive bacilli?
Erysipelothrix -gram-positive bacillus -nonmotile -catalase + -produces H2S -causes Erysipeloid (a skin disease of the hands usually associated with handling infected animals)
307. Resistance to clindamycin can be induced in vitro by
Erythromycin (Erythromycin and clindamycin have similar mechanisms. The presence of erythromycin can induce clindamycin resistance. The D-test is used to detect this inducible resistance)
The appropriate specimen for the diagnosis of mucormycosis is: Nasal swab Sputum Sinus washing Eschar biopsy
Eschar biopsy
128. A positive indole reaction is characteristic of
Escherichia coli
129. Which one of the following organisms would produce a yellow slant and a yellow butt (A/A) on TSI agar after incubating 18 hours?
Escherichia coli
164. A number of vacationers who have traveled outside the U.S. have had their vacations interrupted by a case of "traveler's diarrhea," which is commonly associated with which etiologic agent?
Escherichia coli
182. One of the most common etiologic agents of community-acquired uncomplicated cases of cystitis is
Escherichia coli
347. A 21-year-old sexually active woman came to the university student health service with a 2-day history of urinary frequency with urgency, dysuria, and hematuria. She had no history of prior urinary tract infection. Laboratory test showed a white blood cell count of 10 X 109/L. The urine sediment contained innumerable white cells. Cultures yielded more than 105 colony- forming units/mL of a lactose-fermenting gram-negative rod. The most likely etiologic agent in this case is
Escherichia coli
An organism gave the following reactions: TSI: acid slant/acid butt; no H₂S gas produced Indole: positive Motility: positive Citrate: negative Lysine decarboxylase: positive Urea: negative VP: negative This organism most likely is: Klebsiella pneumoniae Shigella dysenteriae Escherichia coli Enterobacteria cloacae
Escherichia coli
Infection of the urinary tract is most frequently associated with: Staphyloccocus aureus Escherichia coli Enterococcus faecalis Serratia marcescens
Escherichia coli
Which of the following organisms can grow in the small bowel and cause diarrhea in children, travelers diarrhea, or a severe cholera-like syndrome through the production of enterotoxins? Yersinia enterocolitica Escherichia coli Salmonella typhi Shigella dysenteriae
Escherichia coli
Quality contol of the spot indole test requires the use of ATCC cultures of: Pseudomonas aeruginosa/Proteus mirabilis Salmonella typhi/Shigella sonnei Escherichia coli/Proteus vulgaris Escherichia coli/Enterobacter cloacae
Escherichia coli/Enterobacter cloacae
The stock cultures needed for quality control testing of oxidase production are: Escherichia coli/Klebsiella pneumoniae Salmonella typhimurium/Escherichia coli Escherichia coli/Pseudomonas aeruginosa Proteus mirabilis/Escherichia colie
Escherichia coli/Pseudomonas aeruginosa
359. A 7-year-old female became ill with an intestinal illness after visiting a petting zoo featuring farm animals such as calves, lambs, and chickens. She had bloody diarrhea and went on to develop hemolytic uremic syndrome. The most likely etiologic agent in this case is
Eschericia coli 0157:H7 (associated with hemolytic uremic syndrome)
Listeria can be confused with some streptococci because of its hemolysis and because it is: Nonmotile Catalase negative Oxidase postive Esculin positive
Esculin positive
After satisfactory performance of daily disk diffusion susceptibility quality control is documented, the frequency of quality control can be reduced to: Twice a week Every week Every other week Every month
Every week
A liquid fecal specimen from a three-month-old infant is submitted for microbiological examination. In addition to culture on routine media for Salmonella and Shigella, this specimen should be routinely: Examined for the presence of Entamoeba hartmanni Examined for the presence of Campylobacter sp Screened for the detection of enterotoxigenic Escherichia coli Placed in thioglycollate broth to detect Clostridium botulinum
Examined for the presence of Campylobacter sp
Photochromogens produce pigment when: Kept in the dark at 22°C Exposed to light for 1 hour Grown in the presence of CO₂ Incubated with x-ray film
Exposed to light for 1 hour
246. Identify the Fusobacterium sp. considered to be the most frequent isolate recovered from clinical infections.
F. nucleatum Fusobacterium are part of the normal flora of the human mucous membranes, oral cavity, intestines, and urogenital tract.
An aspirate of a deep wound was plated on blood agar plates and incubated aerobically and anaerobically. At 24 hours there was growth on both plates. This indicates that the organism is a(n): Nonfermenter Obligate anaerobe Aerobe Facultative anaerobe
Facultative anaerobe
328. The MIDI identification system is based on
Fatty acid analysis (analyzes fatty acids in the cell walls of microorganisms by using high-performance liquid chromatography for Mycobacterium and gas liquid chromatography for other bacteria and yeasts)
298. The axial fibrils of spirochetes most closely resemble which bacterial structure?
Flagellum
257. Which of the following tests is most appropriate for the presumptive identification of Prevotella melaninogenica?
Fluorescence test -differentiated on laked blood after 5-7 days due to black pigmentation. UV light demonstrates its brick-red fluorescence.
62. Bacillus cereus has been implicated as the etiologic agent in cases of
Food poisoning (associated w/ reheated rice served at Asian restaurants) B. cereus is a Gram +, spore-forming bacilli
Middlebrook 7H10 and 7H11 media must be refrigerated in the dark, and incubated in the dark as well. If these conditions are not met, the media may prove toxic for mycobacteria because: Carbon dioxide will be released Growth factors will be broken down Light destroys the ammonium sulfate Formaldehyde may be produced
Formaldehyde may be produced
77. Which microorganism will grow only on culture media supplemented with either cysteine or cystine?
Francisella tularensis
A yellow colony from a wound culture tested catalase-positive and coagulase-negative. The organism stained as gram-positive cocci in clusters. Which of the following tests would differentiate between a coagulase-negative Staphylococcus and Micrococcus? Novobiocin susceptibility Leucine aminopeptidase production Furazolidone (100 µg/disk) susceptibility Bile esculine
Furazolidone (100 µg/disk) susceptibility
242. The gram-negative, non-spore-forming, anaerobic bacillus frequently implicated in serious clinical infections such as brain and lung abscesses is
Fusobacterium nucleatum -G= anaerobic bacillus -pale-staining bacilli; long, thin with pointed ends
256. Which anaerobic, gram-negative rod can be presumptively identified by its Gram stain morphology, and inhibition by bile and a 1-jag kanamycin disk?
Fusobacterium nucleatum -G= rod with pointed ends. Inhibited by kanamycin and the presence of bile.
261. A curved appearance on Gram stain is characteristic of which of the following?
Fusobacterium nucleatum -thin GNR with pointed ends and a slightly curved appearance in fresh cultures; lose their curviness when subcultured again.
262. Purulent material from a cerebral abscess was submitted to the laboratory for smear and culture. On direct Gram stain, gram-positive cocci in chains and gram-negative bacilli with pointed ends were seen. Plates incubated aerobically exhibited no growth at 24 hours. On the basis of the organisms seen on the smear, what is the most likely presumptive identification of the etiologic anaerobic agents?
Fusobacterium sp. and Peptostreptococcus sp.
157. Which of the following is the most common indicator of bacterial vaginosis?
Gardnerella -small, GNB seen in great numbers on top of epis are called clue cells
87. Campylobacter spp. are associated most frequently with cases of
Gastroenteritis
The following results were obtained from a culture of unknown origin: Gram stain: gram-negative diplococci Indophenol oxidase: positive Glucose: positive Maltose: negative Sucrose: negative The most likely source of the specimen would be the: Respiratory tract Blood Genitourinary tract Cerebrospinal fluid
Genitourinary tract
Which of the following antibiotics would routinely be tested and reported for isolates of Pseudomonas aeruginosa? Penicillin Erythromycin Clindamycin Gentamicin
Gentamicin
322. Which of the following antimicrobial agents acts by inhibiting protein synthesis?
Gentamicin (member of the aminoglycoside group of antibiotics; act on the 30S ribosomal subunit to inhibit protein synthesis; effective against GNB)
284. For non specific staining of Rickettsia the recommended stain is
Gimenez stain
Which 2 diseases are usually preceded by infection with beta-hemolytic streptococci? Rheumatic fever, undulant fever Glomerulonephritis, rheumatic fever Rheumatic fever, tularemia Glomerulonephritis, undulant fever
Glomerulonephritis, rheumatic fever
The preferred carbon source for mycobacteria is: Glycerol Glucose Fatty acids Casein hydrolysate
Glycerol
A beta-hemolytic streptococci that is bacitracin-sensitive and CAMP-negative is: Group B Group A Beta-hemolytic, not group A, B, or D Beta-hemolytic, group D
Group A
A beta-hemolytic Streptococcus that is bacitracin-resistant and CAMP-positive is: Group A or B Group A Group B Beta-hemolytic, group D
Group B
The organism most commonly associated with neonatal purulent meningitis is: Neisseria meningitidis Streptococcus pneumoniae Group B streptococci Haemophilus influenzae
Group B streptococci
A gamma-hemolytic Streptococcus that blackens bile esculin agar but does not grow in 6.5 5 NaCl broth is most likely: Group B Streptococcus Enterococcus Group D Streptococcus Streptococcus pneumoniae
Group D Streptococcus
139. Which of the the following is not true of Haemophilus spp.?
Grow well on sheep blood agar
If present, a characteristic that is helpful in separating Pseudomonas aeruginosa from other members of the Pseudomonas family is: A positive test for cytochrome oxidase Oxidative metabolism in the OF test Production of fluorescein pigment Growth at 42°C
Growth at 42°C
An organism has been identified as a member of the fluorescent group of Pseudomonas. Which of the following sets of tests should be used to determine the species of the organism? Growth at 42°C, pyocyanin production, gelatinase production Pyocyanin production, gelatinase production, OF glucose Growth at 37°C, pyocyanin production, OF glucose Gelatinase production, growth at 52°C, H₂S
Growth at 42°C, pyocyanin production, gelatinase production
A beta-hemolytic streptococcus that has been isolated from an ear culture grows up to the edge of a 0.04 unit bacitracin disk. Which of the following tests would help to determine if the organism is Enterococcus? Growth in 6.5% NaCl broth Growth in the presence of penicillin Optochin susceptibility Fermentation of 10% lactose
Growth in 6.5% NaCl broth
A catheterized urine is inoculated onto blood and MacConkey agar using a 0.01 mL loops. After 48 hours, 68 colonies of a small translucent nonhemolytic organism grew on a blood agar but not the MacConkey. Testing reveals small gram-positive, catalase-negative cocci. The preliminary report and follow-up testing would be: Growth of 680 colonies/mL of gram-positive cocci, optochin and bacitracin susceptibility tests to follow Growth of 6,800 colonies/mL of a Staphylococcus species, coagulase test to follow Growth of 6,800 colonies/mL of a Streptococcus species, esculin hydrolysis and NaCl growth test to follow Growth of 6,800 colonies/mL of a Streptococcus species, no further testing
Growth of 6,800 colonies/mL of a Streptococcus species, esculin hydrolysis and NaCl growth test to follow
193. The porphyrin test is most useful for the identification of which of the following?
Haemophilus
96. A causative agent of the form of conjunctivitis known as pinkeye is
Haemophilus aegyptius -aerobic, GNB, nonmotile, requires both X and V factors to grow.
131. Color Plate 28 shows the Gram stain of cerebrospinal fluid from a 1-year-old girl suspected of having meningitis. After 24 hours of growth, small tan colonies were isolated on chocolate agar incubated in CO2. Sheep blood agar also incubated in CO2 had no growth. Which of the following organisms should be suspected?
Haemophilus influenzae
183. The characteristic growth pattern known as "satelliting" is associated with
Haemophilus influenzae
316. Rapid testing for beta-lactamase production is recommended, before initiation of antimicrobial therapy, for isolates of
Haemophilus influenzae
A 4-year-old boy is admitted to the hospital with suspected meningitis. He has not had most of the childhood vaccines. The suspected pathogen is: Listeria monocytogenes Haemophilus influenzae Streptococcus agalactiae Neisseria meningitidis
Haemophilus influenzae
A cerebrospinal fluid has been inoculated onto sheep blood and chocolate agar plates and into a tube of trypticase soy broth. All media were incubated in an atmosphere of 5% CO₂. Which of the following organisms would usually be isolated by this procedure? Francisella tularensis Haemophilus influenzae Bordetella pertussis Bacteroides fragilis
Haemophilus influenzae
A small, gram-negative bacillus is isolated from an eye culture. It grows only on chocolate agar and is oxidase-variable. The most likely organism is: Acinetobacter lwoffii Haemophilus influenzae Stenotrophomonas maltophilia Pseudomonas aeruginosa
Haemophilus influenzae
An organism that exhibits the satellite phenomenon around colonies of staphylococci is: Haemophilus influenzae Neisseria meningitidis Neisseria gonorrhoeae Klebsiella pneumoniae
Haemophilus influenzae
104. Which of the following has a negative oxidase test?
Hafnia
75. The K antigen of the family Enterobacteriaceae is
Heat labile - can be removed by heating to 100°C for 10-30 minutes.
110. Infection of the gastric mucosa leading to gastritis or peptic ulcers is most commonly associated with
Helicobacter pylori
197. The organism that is linked to peptic ulcers and is the most frequent cause of gastritis is
Helicobacter pylori
A Gram stain of a touch prep from a gastric biopsy shows gram-negative bacilli that are slender and curved. The most likely pathogen is: Burkholderia cepacia Corynebacterium urealyticum Helicobacter pylori Pasteurella multocida
Helicobacter pylori
180. The porphyrin test determines an organism's requirement for
Hemin
Enchephalitis is most commonly associated with which of the following viruses? Epstein-Barr Herpes simplex Coxsackie B Varicella zoster
Herpes simplex
38. Which of the following is a characteristic of staphylococci that would help in their isolation from clinical specimens?
High salt tolerance -Staphylococci not bile resistant, sensitive to novobiocin
103. Campylobacter jejuni is
Hippurate hydrolysis positive -small, curved, GNR, incubated at 42°C with microaerophilic conditions (10% CO2, 5% O2, and 85% N2).
Many fungal infections are transmitted to man via inhalation of infectious structures. Which of the following is usually contracted in this manner? Sporothrix schenckii Trichophyton rubrum Malassezia furfur Histoplasma capsulatum
Histoplasma capsulatum
280. Which of the following is not true about Chlamydophila (Chlamydia) pneumoniae?
Humans become infected from animal reservoirs. (contracted person to person)
175. Which of the following is not true about Pasteurella multocida?
Humans harbor the organism as part of their normal flora.
Definitive identification of Neisseria gonorrhoeae is made with the: Gram stain Oxidase test Degradation of amino acids Hydrolysis of carbohydrates
Hydrolysis of carbohydrates
Which of the following would best differentiate Streptococcus agalactiae from Streptococcus pyogenes? Ability to grow in sodium azide broth A positive bile-esculin reaction Hydrolysis of sodium hippurate Beta-hemolysis on sheep blood agar
Hydrolysis of sodium hippurate
Which feature distinguishes Erysipelothrix rhusiopathiae from other clinically significant non-spore-forming, gram-positive, facultatively anaerobic bacilli? "Tumbling" motility Beta-hemolysis More pronounced motility at 25°C than 37°C H₂S production
H₂S production
153. Foodborne outbreaks of brucellosis are most commonly associated with eating
Imported cheese 4 species are pathogenic to humans: B. abortus, B. melitensis, B. suis, and B. canis.
A first morning sputum is received for culture of acid-fast bacilli. It is digested and concentrated by the N-acetyl-L-cysteine alkali method. Two Sabouraud dextrose slants are incubated in the dark at 35°C with 5-10% CO₂. The smears reveal acid-fast bacilli, but the slants show no growth after 8 weeks. The explanation is: Improper media used Incorrect concetration procedure used Improper specimen submitted Exposure to CO₂ prevents growth
Improper media used
"Nutritionally deficient" streptococci are: Enterococci Group D nonenterococci Cell wall-deficient streptococci In the genera Granulicatella and Abiotrophia
In the genera Granulicatella and Abiotrophia
296. Which of the following is not true of the VDRL test?
Inactivated Treponema pallidum serves as the antigen.
A sputum specimen from a patient with a known Klebsiella pneumoniae infection is received in the laboratory for fungus culture. The proper procedure for handling this specimen is to: Reject the current specimen and request a repeat culture when the bacterial organism is no longer present Incubate culture tubes at room temperature in order to inhibit the bacterial organism Include media that have cycloheximide and chloramphenicol added to inhibit bacterial organisms and saprophytic fungi Perform a direct PAS stain; if no fungal organisms are seen, reject the specimen
Include media that have cycloheximide and chloramphenicol added to inhibit bacterial organisms and saprophytic fungi
271. Chlamydia trachomatis causes which of the following?
Inclusion conjunctivitis also causes trachoma and genital tract infections
To quality control the autoclave, a vial of Bacillus stearothermophilus is autoclaved and should then be: Inoculated to blood agar Incubated at 37°C Inoculated to chocolate agar Incubated at 56°C
Incubated at 56°C
24. When an infection due to Streptomyces is suspected, isolates can be separated from most other bacteria by
Incubating the culture at 25°C -weak pathogens rarely associated with disease -found in soil -S. somaliensis causes myectoma
177. Some strains of Serratia marcescens produce a red-colored pigment. Pigment production is enhanced by
Incubation at 22°C
Gram stain examination of a CSF specimen indicates the presence of yeast-like cells with gram-positive granular inclusions. Which of the following techniques should be used next to assist in the identification of this organism? 10% KOH Lacophenol cotton blue India ink Periodic acid-Schiff
India ink
134. Cardiobacterium hominis, an inhabitant of the upper respiratory tract of humans, has been recovered as the etiologic agent from cases of endocarditis. An identifying characteristic of the organism is
Indole negative -fermentative, GNB, nonmotile, catalase =, oxidase +, weakly indole positive Grows on SBA but enhanced by adding yeast extract to media.
Which one of the following combinations of organisms would be appropriate as controls to test the functions listed? Beta-hemolysis-negative Escherichia coli and Streptococcus pyogenes Catalase-negative Staphylococcus aureus and Staphylococcus epidermidis H₂S production-negative Proteus mirabilis and Staphyloccus epidermidis Indole-negative Escherichia coli and Proteus mirabilis
Indole-negative Escherichia coli and Proteus mirabilis
140. Legionella pneumophila
Infections are most often acquired from environmental sources -does not stain well with Gram -requires special media -motile, biochemically inert, autofluoresce. -airborne transmission
333. Laboratory professionals are at risk for disease transmission. The majority of cases of laboratory-related infections are associated with
Infectious aerosols
239. An infant was seen in the emergency department with symptoms of neuromuscular weakness and constipation. The diagnosis of infant botulism was con- firmed by the demonstration of toxin in the child's stool. The child most likely contracted this disease by
Ingestion of spores that germinated -caused by Clostridium botulinum
In processing clinical specimens and fungal isolates, laboratory workers may contract systemic fungal infections through: Inhalation Ingestion Skin contact Insect vector
Inhalation
283. Human infection with the causative agent of Q fever is acquired by
Inhalation of infectious material Q fever caused by Coxiella burnetii; can resist heat and drying for a long time; does not rely on a bug to be transmitted
305. Penicillin is active against bacteria by
Inhibition or peptidoglycan synthesis
Virus transport medium containing penicillin, gentamicin and amphotericin is used to collect and transport specimens for virus culture because this medium: Enables rapid viral growth during the transport time Inhibits bacterial and fungal growth Destroys nonpathogenic viruses Inhibits complement-fixing antibodies
Inhibits bacterial and fungal growth
In order to isolate Campylobacter coli/jejuni, the fecal specimen should be: Inoculated onto selective plating media and incubated in reduced oxygen with added CO₂ at 42°C Stored in tryptic soy broth before plating to ensure grown of the organism Inoculated onto selective plating media and incubated at both 35°C and at room temperature Incubated at 35°C for 2 hours in Cary-Blair media before inoculating onto selective plating media
Inoculated onto selective plating media and incubated in reduced oxygen with added CO₂ at 42°C
119. Brucella spp. are
Intracellular pathogens small, G= intracellular parasites
Which of the following indicates the presence of viral infection in tissue smears or biopsies? Cytopathic effect Intranuclear inclusions Cell lysis Mononuclear inflammatory cells
Intranuclear inclusions
124. Which of the following is not a characteristic of Klebsiella (Calymmatobacteriuni) granulomatis?
Is isolated on chocolate agar K. granulomatis: pleomorphic, G= encapsulated bacillus (does not Gram stain well). Seen as inclusions in mononuclear cells (Donovan bodies)
161. Why are cultures for Gardnerella vaginalis not recommended?
Isolation of the bacteria may not be clinically significant.
146. Which of the following is not characteristic of Eikenella corrodens?
It is often found in pure culture when recovered from infections. Eikenella corrodens -facultatively anaerobic GNB that requires hemin to grow aerobically
Plesiomonas shigelloides is a relatively new member of the family Enterobacteriaceae. What characteristic separates it from other members of the Enterobacteriaceae? It is oxidase positive It ferments glucose It produces pyocyanin It requires 10% CO₂ for growth
It is oxidase positive
230. Which one of the following is not true of Clostridium tetani?
It produces rapid tissue necrosis. C. tetani - obligate anaerobe
255. Which is a correct statement regarding Clostridium tetani?
It produces terminal spores -Clostridium tetani is a strict anaerobe, terminal round spores, does not utilize carbohydrates. Gelatinase and indole + but nonproteolytic and H2S =
67. The majority of clinical isolates of Klebsiella are
K. pneumoniae Klebsiella have a capsule and appear mucoid on cultures.
211. Which one of the following drugs is not considered as primary antimycobacterial therapy?
Kanamycin
138. Which of the following organisms is unable to grow on MacConkey agar?
Kingella denitrificans - isolated from URT, will grow on MTM, oxidase +. No growth on MAC, poor growth on TSI. Kingella - GNB or cb that may appear in short chains.
208. Mycobacteria can be examined by using the
Kinyoun stain
173. Lack of motility is a characteristic of
Klebsiella
122. Lack of motility is characteristic of
Klebsiella oxytoca Klebsiella, Shigella, Tatumella nonmotile
A sputum culture from an alcoholic seen in the ER grows, mucoid, stringy colonies on sheep blood agar. The isolate grows readily on MacConkey agar and forms mucoid, dark pink colonies. The colonies yield the following test results: ONPG: + Indole: - Glucose: + Oxidase: - Citrate: + VP: + The organism is most likely: Edwardsiella tarda Klebsiella pneumoniae Escherichia coli Proteus vulgaris
Klebsiella pneumoniae
332. Suggested quality control organisms for Simmons citrate agar slants are
Klebsiella pneumoniae (+); Escherichia coli (=)
The stock cultures needed for quality control testing of motility are: Salmonella typhimurium/Escherichia coli Escherichia coli/Pseudomonas aeruginosa Serratia marcescens/Escherichia coli Klebsiella pneumoniae/Escherichia coli
Klebsiella pneumoniae/Escherichia coli
148. Which of the following Legionella spp. is positive for hippurate hydrolysis?
L. pneumophila will autofluoresce
A vaginal/rectal swab is collected from a pregnant patient to screen for group B Streptococcus colonization. What is the best medium to use for specimen inoculation? Blood agar LIM broth CNA agar Thioglycollate broth
LIM broth
Mycoplasmas differ from bacteria in that they: Do not cause disease in humans Cannot grow in artificial inanimate media Lack cell walls Are not serologically antigenic
Lack cell walls
21. Streptococci obtain all their energy from the fermentation of sugars to
Lactic acid -Streptococci are catalase = and are normal flora of the skin, throat, and intestine
327. During childbearing years, the normal flora of the vagina is predominantly
Lactobacillus
253. Small alpha-hemolytic colonies are seen on a sheep blood agar plate after 48 hours of incubation on a vaginal culture. This describes which of the following?
Lactobacillus -green discoloration on chocolate agar
270. Which bacterium is part of the normal vaginal flora that helps resist the onset of bacterial vaginosis?
Lactobacillus sp.
Which of the following is most often used to prepare a slide form a plate culture of a dermatophyte for microscopic observation? Lactophenol cotton blue Potassium hydroxide Iodine solution Gram stain
Lactophenol cotton blue
95. Neisseria lactamica closely resembles Neisseria meningitidis but can be differentiated from it by its ability to metabolize
Lactose Differentiate by using the ONGP test (fermentation of lactose).
Which of the following is the most reliable test to differentiate Neisseria lactamica from Neisseria meningitidis? Acid from maltose Growth on modified Thayer-Martin agar Lactose degradation Nitrite reduction to nitrogen gas
Lactose degradation
84. Salmonella Typhi exhibits a characteristic biochemical pattern, whichdifferentiates it from the other salmonellae. Which of the following is not characteristic of S. Typhi?
Large amounts of H2S are produced in TSI agar. -S. typhi produces a small amount of H2S, produces no gas from glucose, is citrate negative, and possesses a capsular antigen (Vi).
70. Which of the following is not true of Shigella sonnei?
Large numbers of organisms must be ingested to produce disease.
A beta-hemolytic gram-positive coccus was isolated from the cerebrospinal fluid of a 2-day-old infant with signs of meningitis. The isolate grew on sheep blood agar under aerobic conditions and was resistant to a bacitracin disk. Which of the following should be performed for the identification of the organism? Oxidase production Catalase formation Latex antigen typing Esculin hydrolysis
Latex antigen typing
Group B, beta-hemolytic streptococci may be distinguished from other hemolytic streptococci by which of the following procedures? Latex antigen typing Growth in 6.5% NaCl broth Growth on bile esculin medium Bacitracin susceptibility
Latex antigen typing
336. The paper strip test for the demonstration of hydrogen sulfide production is impregnated with a solution of
Lead acetate
267. Egg yolk agar showing a precipitate in the medium surrounding the colony is positive for
Lecithinase production -C. perfringens is + for lecithinase production
360. A middle-aged man with a history of smoking and drinking for over 40 years developed shortness of breath, fever, frontal headache, diarrhea, and cough. He worked in the produce section of a supermarket, which routinely misted the fresh greens. His medical history included a kidney transplant several years ago for which he remains on antirejection therapy. His sputum Gram stain showed numerous polymorphonuclear cells but rare microorganisms. An X-ray of his chest showed an infiltrate in the left lower lobe, and a diagnosis of atypical pneumonia was made. Which of the following is the most likely etiologic agent in this case?
Legionella pneumophila
162. Buffered charcoal yeast extract agar is the recommended medium for the recovery of
Legionella pneumophila - requires cysteine and cystine for growth like Francisella tularensis.
294. A helicoidal, flexible organism was demonstrated in a blood smear. This motile organism was approximately 12 um long, approximately 0.1 um wide, and had semicircular hooked ends. The description of this organism corresponds most closely to the morphology of
Leptospira
355. Several international participants in an Eco-Challenge adventure race in Borneo became ill with symptoms of chills, diarrhea, headaches, and eye infections. The racers hiked in the mountains and jungles, swam in rivers, and slogged through flooded streams for 2 weeks. Contact with contaminated water and soil during the race was highly associated with illness. What is the most likely etiologic agent in this case?
Leptospira interrogans causes Weil disease
50. Which of the following is catalase negative?
Leuconostoc -vancomycin resistant
295. The etiologic agent of epidemic relapsing fever is Borrelia recurrentis, which is commonly transmitted by
Lice (human body louse)
201. Mycobacteria have a large amount of a component in their cell wall that other bacteria lack. That component is
Lipids - must be acid-fast stained because of this
212. In the decontamination and digestion procedure for the isolation of mycobacteria from sputa samples, what is the role of NALC?
Liquefies mucus
The function of N-acetyl-L-cysteine is the reagent for acid-fast digestion-decontamination procedure is to: Inhibit growth of normal respiratory flora Inhibit growth of fungi Neutralize the sodium hydroxide Liquefy the mucus
Liquefy the mucus
6.1. Which of the following is associated with infections in humans often linked to deli meats and improperly pasteurized dairy products?
Listeria monocytogenes
12. Color Plate 26 • shows the Gram stain of a blood culture on a 23-year-old pregnant woman who presented with fever and flulike symptoms in her ninth month. The isolate on blood agar produced small, translucent beta-hemolytic colonies. Which of the following is the most likely etiologic agent in this case?
Listeria monocytogenes -GPR -motile at room temp, not at 35°C. -hydrolyzes esculin -catalase + -oxidase = -beta-hemolytic on SBA; confused with group A or B strep as a result
358. A woman, who had recently returned from a vacation in Mexico, was admitted to the hospital. She was febrile and complained of flulike symptoms. Her case history revealed that she had eaten cheese that had been made from unpasteurized milk while on vacation. The most likely etiologic agent in this case would be
Listeria monocytogenes (associated with unpasteurized dairy products)
26. Growth in a 48-hour semisolid agar stab culture at room temperature reveals lateral filamentous growth away from the stab near the top of the medium. This observation is most characteristic of which organism?
Listeria monocytogenes - motile at room temperature, nonmotile at 35°C.
The best medium for culture of Mycobacterium tuberculosis is: Bordet-Gengou agar Loeffler medium Lowenstein-Jensen medium Cystine blood agar
Lowenstein-Jensen medium
Which of the following combinations of media provides an egg base, agar base, and a selective egg or agar base media? Lowenstein-Jensen, American Throacic Society (ATS), Middelbrook 7H11 Lowenstein-Jensen, Middlebrook 7H11, Lowenstein-Jensen Gruft Middlebrook 7H10, Petragnani, Lowenstein-Jensen Middlebrook 7H10, Middlebrook 7H11, Mitchison 7H11
Lowenstein-Jensen, Middlebrook 7H11, Lowenstein-Jensen Gruft
326. Which of the following body sites is not normally colonized by large numbers of normal flora organisms?
Lungs
354. In August, a patient presented at a community hospital in New England with symptoms of a skin rash, headache, stiff neck, muscle aches, and swollen lymph nodes. A silver-stained biopsy of a skin lesion showed spirochetes. On the basis of the clinical syndrome and laboratory detection of a causative agent, the patient was diagnosed as having
Lyme disease tick-borne disease caused by Borrelia burgdorferi
297. Borrelia burgdorferi, a spirochete transmitted by Ixodes dammini in the northeastern U.S., is the etiologic agent of
Lyme disease (transmitted by a tick)
289. A screening test for the identification of Mycoplasma pneumoniae isolates is the
Lysis of red blood cells M. pneumoniae produces hydrogen peroxide which lyses RBCs. Grown on SP4 agar. Add guinea pig RBCs and a small zone of beta-hemolysis will develop.
215. Which of the following Mycobacterium is most noted for being associated with patients with acquired immunodeficiency syndrome?
M. avium-intracellularae complex
219. Susceptibility to thiophene-2-carboxylic acid hydrazide (T2H) is characteristic of which of the following mycobacteria?
M. bovis
214. Which of the following is associated with livestock and causes a zoonosis?
M. bovis -negative for niacin production and nitrate reduction
203. Mycobacterium fortuitum, a rapidly growing Mycobacterium, grows on MacConkey agar in 5 days. Which other species of Mycobacterium is able to demonstrate growth within the same time period on MacConkey agar?
M. chelonei M. fortuitum and M. chelonei are the only mycobacteria that grow on MAC at 5 days.
216. Which of the following Mycobacterium produces an orange pigment and is most commonly recovered from water?
M. gordonae - "tap water scotochromogen"; slow growing, form yellow-orange colonies that do not depend on exposure to light
221. The most common photochromogenic Mycobacterium isolated in the U.S. is
M. kansasii
218. The Mycobacterium that is the etiologic agent of "swimming pool granuloma" is
M. marinum optimal growth at 25-35°C
217. Which of the following Mycobacterium appears as buff-colored colonies after exposure to light and is niacin positive?
M. tuberculosis
210. Which of the following mycobacteria has an optimal growth temperature 30-32°C?
M. ulcerans M. ulcerans and M. marinum optimal growth at 30-32°C. Poor growth at 37°C.
202. The species of Mycobacterium that would be most commonly associated with contamination of the hot water system in large institutions such as hospitals is
M. xenopi
The major features by which molds are routinely identified are: Macroscopic characteristics and microscopic morphology Biochemical reactions and microscopic morphology Macroscopic characteristics and selective media Specialized sexual reproductive structures
Macroscopic characteristics and microscopic morphology
34. An identifying characteristic of Staphylococcus aureus is
Mannitol fermentation postive -S. aureus is coagulase and DNase +, and is able to grow in high salt concentrations.
335. Which of the following media is both selective and differential?
Mannitol salt agar (used for the isolation and identification of staphylococcal species)
342. Continuous blood culture systems that detect changes in headspace pressure in bottles are referred to as
Manometric methods
A cell culture line used for the recovery of Chlamydia trachomatis from clinical specimens is: HeLa 229 Hep-2 BHK-21 McCoy
McCoy
Assuming the agent isolated from a patients spinal fluid produces a positive oxidase test, the most likely diagnosis is: Tuberculosis meningitis Miningococcal meningitis Viral meningitis Pneumococcal meningitis
Meningococcal meningitis
159. Yersinia pseudotuberculosis is known to manifest commonly as which of the following clinical conditions?
Mesenteric lymphadenitis Yersinia pseudotuberculosis - G= cb, grows well in routine media, optimal growth at 25-30°C.
266. To ensure that anaerobic conditions have been achieved in anaerobic jars or chambers, an oxygen-sensitive indicator is employed, such as
Methylene blue
312. Which drug known to be active against parasitic infections has importance as a therapeutic agent in cases of disease caused by anaerobic bacteria?
Metronidazole (drug recommended for the treatment of amebic dysentery and trichomoniasis acts by inhibiting DNA synthesis)
7. A gram-positive coccus that is catalase positive, nonmotile, lysostaphin resistant, and modified oxidase positive is best identified as a member of the genus
Micrococcus Micrococci and Staphylococci are both catalase + GPC. Micrococci is modified oxidase positive, Staphylococci are negative.
The lowest concentration of antibiotic that inhibits growth of a test organism: Minimum inhibitory concentration Serum inhibitory concentration Minimum bactericidal titer Maximum inhibitory titer
Minimum inhibitory concentration
238. The anaerobic, gram-negative, curved, motile bacilli associated with bacterial vaginosis belong to the genus
Mobiluncus
265. Aspiration of vomitus can lead to pneumonia. Which of the following would not be a likely causative agent in aspiration pneumonia?
Mobiluncus sp. Common causes of aspiration pneumonia: -Prevotella, Porphyromonas, Bacteroides, fusobacteria, anaerobic streptococci
142. Which of the following is not an appropriate medium for primary isolation of Bordetella pertussis?
Modified Skirrow's medium - used for Campylobacter spp.
346. A purulent aspirate of joint fluid from a 28- year-old female with joint pain was sent for microbiologic examination. The Gram stain of this sample revealed many polymorphonuclear cells with intracellular and extracellular gram-negative diplococci. Given the specimen type and microscopic findings, the appropriate selective medium for primary isolation would be
Modified Thayer-Martin agar
133. Of the following microorganisms, which one will turn a dark purple when tetramethyl-p-phenylenediaminehydrochloride (oxidase reagent) is applied?
Moraxella catarrhalis
A Gram stain performed on a sputum specimen revealed gram-negative diplococci within PMNs. Oxidase testing is positive and carbohydrate degradation tests are inert. The organism is: Neisseria lactamica Moraxella catarrhalis Neisseria meningitidis Neisseria sicca
Moraxella catarrhalis
Which of the following organisms may be mistaken for Neisseria gonorrhoeae in Gram stained smears of uterine cervix exudates? Lactobacillus species Streptococcus agalactiae Pseudomonas aeruginosa Moraxella osloensis
Moraxella osloensis
The best procedure to differentiate Listeria monocytogenes from Corynebacterium species is: Catalase Motility at 25°C Motility at 35°C Gram stain
Motility at 25°C
310. The agar recommended by the Clinical and Laboratory Standards Institute for routine susceptibility testing of nonfastidious bacteria is
Mueller-Hinton agar
315. Which of the following media should be used for in vitro susceptibility testing of S. pneumoniae?
Mueller-Hinton base supplemented with 5% lysed horse blood
302. When testing the antimicrobial susceptibility of Haemophilus influenzae strains by disk-agar diffusion, the recommended medium is
Mueller-Hinton base supplemented with hematin, NAD, and yeast extract
Which one of the following species of Mycobacterium does not usually fluoresce on fluorochrome stain? Mycobacterium fortuitum Mycobacterium tuberculosis Mycobacterium ulcerans Mycobacterium bovis
Mycobacterium fortuitum
206. The etiologic agent of Hansen disease (leprosy) is
Mycobacterium leprae
357. A college student got a summer job working at a marina. While repairing the outboard motor on a rental boat, he received several lacerations on his right forearm. No medical treatment was sought at the time of the injury, but after several weeks he noted that the lesions were not healing and he sought the opinion of his physician. A biopsy of one of the lesions revealed a cutaneous granulomatous condition. Given the history, which of the following microorganisms would most likely be the etiologic agent in this case?
Mycobacterium marinum
204. A slowly growing , orange-pigmented, acid-fast bacillus was isolated from a cervical lymph node of a child with symptoms of cervical adenitis. The most likely etiologic agent in this case would be
Mycobacterium scrofulaceum -scotochromogen because it produces pigmentation in the dark.
282. Colonies said to have the appearance of a "fried egg" are characteristic of
Mycoplasma hominis
273. The etiologic agent of primary atypical pneumonia is
Mycoplasma pneumoniae
279. Which of the following Mycoplasmataceae has not been connected with human genital infections?
Mycoplasma pneumoniae (RESPIRATORY TRACT PATHOGEN)
Which of the following reagents should be used as a mucolytic, alkaline reagent for digestion and decontamination of a sputum for mycobacterial culture? N-acetyl-L-cystine and NaOH NaOH alone Zephiran-trisodium phosphate Oxalic acid
N-acetyl-L-cystine and NaOH
154. Serratia spp. are unique in the family Enterobacteriaceae because of their ability to produce extracellular hydrolytic enzymes. Which of the following is not produced by Serratia species?
NADase
205. When clinical specimens are processed for the recovery of Mycobacterium tuberculosis, the generally recommended method for digestion and decontamination of the sample is
NALC-NaOH
185. When an epidemiologic survey for the detection of upper respiratory tract carriers of Neisseria meningitidis or Bordetella pertussis is being conducted, the optimal type of specimen to be obtained for culture is
Nasopharyngeal
Respiratory syncytial virus is best isolated using a(n): Nasopharyngeal aspirate Cough plate Expectorated sputum Throat swab
Nasopharyngeal aspirate
156. The optimal specimen for the recovery of Bordetella pertussis is
Nasopharyngeal swab Inoculate in Regan-Lowe media, add cephalexin to inhibit the growth of normal flora
168. Which of the Neisseria spp. produces acid from glucose but not from maltose, lactose, or sucrose?
Neisseria gonorrhoeae
198. New York City agar was developed for the isolation of
Neisseria gonorrhoeae
94. Erythromycin eye drops are routinely administered to infants to prevent infections by
Neisseria gonorrhoeae
Clinical resistance to penicillin correlates most frequently with beta-lactamase production in: Neisseria gonorrhoeae Neisseria meningitidis Streptococcus agalactiae Streptococcus pyogenes
Neisseria gonorrhoeae
Coagglutination is associated with: Chlamydia trachomatis Neisseria gonorrhoeae Streptococcus pneumoniae Klebsiella pneumonia
Neisseria gonorrhoeae
166. The flattened adjacent sides of the cellular appearance of which microorganism are said to resemble kidney beans?
Neisseria gonorrhoeae G= diplococci
350. A 3-year-old was brought to the emergency department by her parents. She had been febrile with a loss of appetite for the past 24 hours. Most recently the parents noted that it was difficult to arouse her. She attended a daycare center, and her childhood immunizations were current. On examination she demonstrated a positive Brudzinski sign indicative of meningeal irritation. Cultures of blood and cerebrospinal fluid (CSF) were sent to the laboratory. Her CSF was cloudy, and the Gram stain showed many polymorphonuclear cells containing gram-negative diplococci. The white blood cell count was 25 X 109/L, with 88% polymorphonuclear cells. The CSF protein was 100 mg/dL, and the glucose was 15 mg/dL. Cultures of the blood and CSF grew the same organism. The most likely etiologic agent in this case is
Neisseria meningitidis
An autopsy performed on an 8-year-old child revealed Waterhouse-Friderichsen syndrome. Blood and throat cultures taken just prior to death were positive for which organism? Neisseria gonorrhoeae Neisseria meningitidis Haemophilus influenzae Klebsiella pneumoniae
Neisseria meningitidis
92. A gram-negative, "kidney bean" cellular morphology is a distinguishing characteristic of
Neisseria meningitidis N. meningitidis and N. gonorrhoeae have a "kidney bean" cellular morphology.
82. Severe disseminated intravascular coagulation often complicates cases of septicemia caused by
Neisseria meningitidis The Waterhouse-Friderichsen syndrome of disseminated intravascular coagulation occurs in cases of fulminant meningococcemia - Neisseria meningitidis septicemia.
169. Which of the Neisseria spp. produces acid from glucose and maltose but not sucrose or lactose?
Neisseria meningitidis oxidase +, G= diplococci
The most sensitive substrate for the detection of beta-lactamase is: Penicillin Ampicillin Cefoxitin Nitrocefin
Nitrocefin
Which of the following antimicrobials would be inappropriate to report on an E coli isolated from a wound culture? Gentamicin Ampicillin Cefazolin Nitrofurantoin
Nitrofurantoin
An organism recovered from a sputum has the following characteristics: Culture: growth at 7 days on Lowenstein-Jensen agar, incubated under aerobic conditions with CO₂ at 35°C Gram stain: delicate branching gram-positive bacilli Acid-fast stain: Branching, filamentous, "partially" acid-fast bacterium These results are consistent with which of the following genera? Nocardia Mycobacterium Actinomyces Streptomyces
Nocardia
49. A bone marrow transplant patient on immunosuppressive therapy developed a pulmonary abscess with symptoms of neurologic involvement. A brain abscess was detected by MRI, and aspirated material grew an aerobic, filamentous, branching gram-positive organism, which stained weakly acid-fast. The most likely etiologic agent in this case would be
Nocardia asteroides
A branching gram-positive, paritally acid-fast organism is isolated from a bronchial washing on a 63-year-old woman receiving chemotherapy. The organism does not hydrolyze casein, tyrosine or xanthine. The most likely identification is: Actinomadura madurae Nocardia caviae Streptomyces somaliensis Nocardia asteroides
Nocardia asteroids
29. Nocardia can be differentiated from Actinomyces based on
Nocardia being catalase positive -Actinomyces is catalase =, gram +, non-spore-forming anaerobic bacilli. "Sulfur granules" are characteristic. -Nocardia are catalase + aerobic organisms.
209. Which of the following is not characteristic of Mycobacterium kansasii?
Non chromogenic (slowly growing photochromogen) -Obligate aerobic bacilli, exhibit acid fastness
117. Which of the following is not true regarding virulent strains of Vibrio cholerae?
Nonmotile
Shigella species characteristically are: Urease positive Nonmotile Oxidase positive Lactose fermenters
Nonmotile
A urine Gram stain shows gram-positive cocci in clusters. The organism tested catalase positive. To speciat⁵ this organism from culture, the technician should perform a coagulase test and a/an: Polymyxin B susceptibility Novobiocin susceptibility Oxidase Beta-lactamase
Novobiocin susceptibility
AFB smear positive respiratory specimens may be reliably identified as Mycobacterium tuberculosis the same the day the smear was read by: Cording seen on the AFB smear Nucleic acid amplification QuantiFERON-TB test DNA probes
Nucleic acid amplification
106. The method of serogrouping Shigella used in the clinical laboratory is based on
O antigens (somatic oligosaccharide) Nonmotile so H or flagella antigens cannot be used, H antigens are used for Salmonella and E. coli. Capsular (K) antigens used for Klebsiella.
118. The classic toxigenic strains of which serogroup are implicated in epidemic infections of Vibrio cholerae?
O1
339. The medium used to determine whether an organism is oxidative or fermentative with respect to its metabolic activities is
OF medium
178. Which of the following is not a correct description regarding Aeromonas hydrophila?
ONPG negative
321. Metronidazole is most commonly recommended for treatment of infections caused by
Obligate anaerobic microorganisms Metronidazole acts to disrupt bacterial DNA through the production of cytotoxic intermediates
Which one of the following results is typical of Campylobacter jejuni: Optimal growth at 42°C Oxidase negative Catalase negative Nonmotile
Optimal growth at 42°C
Three sets of blood cultures were obtained from an adult patient with fever and suspected endocarditis. The aerobic bottle of one set had growth of Staphylococcus epidermidis at 5 days of incubation. This indicates that: Ther ewas low-grade bacteremia The organism is most likely a contaminant The patient has a line infection The blood culture bottles are defective
Organism is most likely a contaminant
An urethral swab obtained from a man with an urethral exudate was plated directly on chocolate agar and modified Thayer-Martin agar, and a Gram stain was made> The Gram stain showed gram-negative diplococci. The culture plates were incubated at 35°C, but had no growth at 48 hours. The most likely failure for organism growth is that the: Wrong media were used Gram stain was misread Organism only grows at room temperature Organism requires CO₂ for growth
Organism requires CO₂ for growth
An expectorated sputum is sent to the laboratory for culture from a patient with respiratory distress. The Gram stain of the specimen shows many squamous epithelial cells (>25/lpf) and rare neutrophils. The microscopic appearance of the organisms present include: Moderate GPC in chains and diplococci Moderate GNDC Moderate palisading GPB This Gram stain is MOST indicative of: A pneumococcal pneumonia An anaerobic infection An Haemophilus pneumonia Oropharyngeal flora
Oropharyngeal flora
Haemophilus influenzae is most likely considered normal indigenous flora in the: Oropharynx Female genital tract Large intestine Small intestine
Oropharynx
244. Which of the following statements is not characteristic of Clostridium botulinum?
Oval spores are located terminally.
A 73-year-old man diagnosed as having pneumococcal meningitis is not responding to his penicillin therapy. Which of the following tests should be performed on the isolate to best determine this organisms susceptibility to penicillin? Beta-lactamase Oxacillin disk diffusion Penicillin disk diffusion Schlichter test
Oxacillin disk diffusion
The method used for processing specimens for mycobacterial culture contaminated with Pseudomonas is: N-acetyl-L-cystine and NaOH NaOH Zephiran-trisodium phosphate Oxalic acid
Oxalic acid
Differentiating tests that will separate Burkholderia from Stenotrophomonas include: Gram stain reaction Growth on MacConkey agar Glucose fermentation Oxidase
Oxidase
A gram-negative diplococcus that grows on modified Thayer-Martin medium can be further confirmed as Neisseria gonorrhoeae if it is: Oxidase positive, glucose positive, and maltose positive Oxidase positive and glucose positive, maltose negative Oxidase positive and maltose positive, glucose negative Glucose positive, oxidase negative and maltose negative
Oxidase positive and glucose positive, maltose negative
147. Which of the following species of Pasteurella is associated with human infections following cat bites?
P. multocida -G= cb -penicillin is effective
213. Which one of the following tests would be appropriate in the diagnosis of a mycobacterial infection?
PPD test
6. Streptococcus pyogenes can be presumptively identified using a(n)
PYR disk
The genus of virus associated with anogenital warts, cervical dysplasia and neoplasia is: Herpes simplex virus Papillomavirus Cytomegalovirus Coxsackievirus
Papillomavirus
Organisms that can be easily identified to the species level from the ova in fecal specimens include: Metagonimus yokogawai, Heterophyes heterphyes Taenia solium, Taenia saginata Necator americanus, Ancylostoma duodenale Paragonimus westermani, Hymenolepis nana
Paragonimus westermani, Hymenolepis nana
An isolate on chocolate agar from a patient with epiglottitis was suggestive of Haemophilus species. Additional testing showed that the isolate required NAD for growth and was nonhemolytic. The organism is most likely Haemophilus: Haemolyticus Ducreyi Influenzae Parainfluenzae
Parainfluenzae
A gram-negative bacillus with bipolar staining was isolated from a wound infection caused by a bite from a pet cat. The following characteristic reactions were seen: Oxidase: positive Glucose OF: fermentive Catalase: positive Motility: negative MacConkey agar: no growth Which of the following is the most likely organism? Pseudomonas aeruginosa Pasteurella multocida Aeromonas hydrophila Vibrio cholerae
Pasteurella multocida
9. Erysipelothrix infections in humans characteristically produce
Pathology at the point of entrance of the organism -main infection: erysipeloid which presents with cutaneous spreading lesions of the fingers or hand that are raised and erythematous.
123. In cases of legionellosis
Patients can present with a self-limited nonpneumonic febrile illness Legionella pneumophila causes Legionellosis and Pontiac fever. Optimal temp. for cultivation is 35°C
309. Beta-lactamase-producing strains of Haemophilus influenzas are resistant to
Penicillin
An antibiotic that inhibits cell wall synthesis is: Chloramphenicol Penicillin Sulfamethoxazole Colistin
Penicillin
268. After 72 hours of anaerobic incubation, small olive-green to black colonies are seen. A Gram stain reveals gram-postive cocci. What is the most likely identification of this organism?
Peptococcus niger
234. Which of the following is described as obligately anaerobic gram-positive cocci?
Peptostreptococcus
After 24 hours of a blood culture from a newborn grows catalase-negative, gram-positive cocci. The bacterial colonies are small, transluscent and beta-hemolytic on a blood agar plate. Biochemical test results of a pure culture are: Bacitracin: Resistant CAMP reaction: Positive Bile esculin: Not hydrolyzed 6.5% NaCl broth: No growth Assuming that all controls react properly and reactions are verified, the next step would be to: Perform a Streptococcus group typing Report the organism as Streptococcus pneumoniae Report the organism as Staphylococcus aureus Report the organism as Staphylococcus epidermidis
Perform a Streptococcus group typing
19. Staphylococcus aureus, when present, could most likely be recovered from a stool sample if the primary plating medium included
Phenylethyl alcohol -Phenylethyl alcohol agar (PEA) is selective for GPC. Phenylethyl alcohol inhibits G= aerobic bacilli. -PEA inhibits swarming by Proteus spp.
Mycobacteria that produce pigment only after exposure to light are classified as: Photochromogens Scotochromogens Nonchromogens Rapid growers
Photochromogens
Which of the following groups of specimens would be acceptable for anaerobic culture? Vaginal, eye Ear, leg tissue Pleural fluid, brain abscess Urine, sputum
Pleural fluid, brain abscess
In the optochin (ethylhydrocupreine hydrochloride) susceptibility test, if there is a zone of inhibition of 19-30 mm surrounding the disk following overnight incubation at 37°C, the colony most likely consists of: Staphylocci Streptococci Pneumococci Intestinal bacilli
Pneumococci
Artifacts found in a stool specimen that can be confused with ova or cysts are: Partially digested meat fibers Degenerated cells from the gastrointenstinal mucosa Dried chemical crystals Pollen grains
Pollen grains
263. Which of the following is an important virulence factor of Bacteroides fragilis?
Polysaccharide capsule
99. Legionella pneumophila is the etiologic agent of both Legionnaires disease and
Pontiac fever
A Gram stain of organisms on Loeffler agar showed pleomorphic gram-positive bacilli. The organism should be subcultured to: Blood Chocolate MacConkey Potassium tellurite
Potassium tellurite
290. A genital specimen is inoculated into 10B broth. After overnight incubation, an alkaline reaction is noted without turbidity. What is the most likely explanation?
Presence of Ureaplasma urealyticum
The characteristic that is most commonly associated with the presence of strict anaerobic bacteria and can be taken as presumptive evidence of their presence in a clinical specimen is the: Presence of a signle bacterial species Production of gas in a thioglycollate broth culture Growth on a blood agar plate incubated in an anaerobic jar Presence of a foul, putrid odor from tissue specimens and cultures
Presence of a foul, putrid odor from tissue specimens and cultures
245. A tube of semisolid medium that contains resazurin appears pink. What does this indicate?
Presence of oxygen Resazurin indicator looks colorless is low [O2] and pink in high [O2]
229. A cervical mucosal abscess specimen was sent to the laboratory for bacteriologic examination. The culture of this sample grew an anaerobic gram-negative bacillus that was inhibited by bile, produced a black pigment, and was negative for indole production and positive for glucose, sucrose, and lactose fermentation. This isolate would most likely be
Prevotella melaninogenica - black pigment occurs on laked blood agar plates; brick-red fluorescence under UV light.
A bronchial washing is processed for acid-fast bacilli. Which of the following precautions should be taken in order to prevent infection of laboratory personnel? Add an equal amount of NALC to the specimen Process all specimens under ultraviolet light Centrifuge specimen only after the addition of preservative Process all specimens in a biological safety hood
Process all specimens in a biological safety hood
Which characteristic best differentiates Acinetobacter species from Moraxella species? Production of indophenol oxidase Growth on MacConkey agar Motility Susceptibility to penicillin
Production of indophenol oxidase
344. In the catalase test, the formation of bubbles is due to
Production of oxygen (O2) Hydrogen peroxide is reduced to water and oxygen. Staph are + and strep are =
243. Which one of the following is a non-spore-forming, gram-positive, anaerobic bacillus?
Propionibacterium
240. The majority of the gram-positive, non-spore-forming, anaerobic bacilli isolated from clinical material will be
Propionibacterium acnes -normal flora of the skin; common contaminant of blood cultures because of this.
>100,000 CFU/mL of a gram-negative bacilli were isolated on MacConkey from a urine specimen. Biochemical results are as follows: Glucose: acid, gas produced Indole: negative Urea: positive TDA: positive H₂S: positive The organism is most likely: Morganella morganii Proteus mirabilis Proteus vulgaris Providencia stuartii
Proteus mirabilis
144. A gram-negative bacillus was recovered from the urine of a child with a history of recurrent urinary tract infections. The organism was oxidase negative, lactose negative, urease positive, and motile. The most likely identification of this agent would be
Proteus mirabilis phenylalanine deaminase +
A urine culture had the following culture results: Sheep blood: swarming Columbia CNA: no growth MacConkey: 1) >100,000 CFU/mL nonlactose-fermenter 2) >100,000 CFU/mL nonlactose-fermenter with red pigment The isolates from MacConkey agar had the following biochemical reactions: Isolate 1: TSI: alk/acid Urea: positive TDA: positive H₂S: positive Isolate 2: TSI: alk/acid Urea: negative TDA: negative H₂S: negative The organisms are most likely: Proteus vulgaris and Enterobacter cloacae Proteus mirabilis and Serratia marcescens Morganella morganii and Klebsiella pneumoniae Providencia stuartii and Serratia liquefaciens
Proteus mirabilis and Serratia marcescens
172. A positive phenylalanine deaminase reaction is characteristic of
Proteus vulgaris
136. Which of the following organisms produce a positive phenylalanine deaminase reaction?
Providendia stuartii Proteus vulgaris, Providencia stuartii, Morganella morganii, Tatuella ptyseos are phenylalanine deaminase positive.
152. In the past, povidone iodine, tincture of iodine prep pads and swabs, and other disinfectants have been recalled because of microbial contamination. The most likely organism to be isolated in these cases is
Pseudomonas aeruginosa
163. Swimmer's ear, a form of external otitis is commonly caused by
Pseudomonas aeruginosa
188. Association with faucet aerators and humidifiers used with ventilators in intensive care units is commonly a factor in outbreaks of infections with which of the following microorganisms?
Pseudomonas aeruginosa
196. A young man developed keratitis associated with the use of contact lenses that had been immersed in a contaminated cleaning solution. The most common bacterial etiologic agent in such cases is
Pseudomonas aeruginosa
79. An example of an oxidase-positive, glucose nonfermenting organism is
Pseudomonas aeruginosa
A nonfermenting gram-negative bacillus is isolated from a wound. The nitrate and oxidase are strongly positive. The growth on sheep blood agar has a grape-like odor. The organism is: Burkholderia cepacia Moraxella lacunata Chryseobacterium (Flavobacterium) meningosepticum Pseudomonas aeruginosa
Pseudomonas aeruginosa
An organism isolated from the surface of a skin burn is found to produce a diffusible green pigment on a blood agar plate. Further studies of the organism would most likely show the organism to be: Staphylococcus aureus Serratia marcescens Flavobacterium meningosepticum Pseudomonas aeruginosa
Pseudomonas aeruginosa
176. Pus was aspirated from an empyema. A Gram stain of the aspirated material showed many white blood cells and numerous gram-negative bacilli. The culture grew many colonies producing a soluble green pigment. The most likely etiologic agent in this case would be
Pseudomonas aeruginosa -grapelike odor -blue-green color -motility and oxidase + -able to grow at 42°C
130. Pyocyanin is characteristically produced by
Pseudomonas aeruginosa ONLY -grape-like odor, blue-green pigment
137. Which of the following non-lactose-fermenting organisms does not produce fluorescein?
Pseudomonas alcaligenes Yellow pigment fluorescein (pyoverdin) produced by Pseudomonas aeruginosa, P. fluorescens, and P. putida. Use cetrimide when trying to detect pyoverdin.
86. Which of the following diseases is most likely to be acquired from a hot tub or whirlpool?
Pseudomonas dermatitis
4. Abiotrophia, formerly known as nutritionally variant streptococci, will not grow on routine blood or chocolate agars because they are deficient in
Pyridoxal
When staining acid-fast bacilli with Truant auramine-rhodamine stain, potassium permanganate is used as a: Decolorizing agent Quenching agent Mordant Dye
Quenching agent
325. When using the rapid chromogenic cephalosporin method for the detection of beta-lactamase production by an organism, a positive test is indicated by the color
Red Yellow compound turns red if the organism produces the enzyme that breaks the beta-lactam ring. Nitrocefin, the most commonly used compound, has a high affinity for most bacterial beta-lactamases.
Members of the family Enterobacteriaceae share which one of the following characteristics? Produce cytochrome oxidase Ferment lactose Produce beta-hemolysis Reduce nitrate to nitrite
Reduce nitrate to nitrite
The best medium for culture of Bordetella pertussis is: Regan-Lowe agar Cystine blood agar Martin Lewis agar Ashdown agar
Regan-Lowe agar
A 21-year-old patient presents with pharyngitis. A throat swab is collected and submitted for anaerobic culture. This specimen should be: Set up immediately Rejected as unacceptable Inoculated into thioglycollate broth Sent to a reference laboratory
Rejected as unacceptable
Characteristically, enterococci are: Unable to grow in 6.5% NaCl Relatively resistant to penicillin Sodium hippurate positive Bile esculin negative
Relatively resistant to penicillin
A liquid stool specimen is collected at 10:00 pm and brought to the laboratory for culture and ova and parasite examination. It is refrigerated until 10:10 am the next day, when the physician requests that the technologist look for amoebic trophozoites. The best course of action would be to: Request a fresh specimen Perform a concentration on the original specimen Perform a trichrome stain on the original specimen Perform a saline wet mount on the original specimen
Request a fresh specimen
127. Isolation of Neisseria gonorrhoeae
Requires incubation under increased CO2 Sensitive to drying and low temperatures
277. Which of the following is true about mycoplasmas?
Resistant to penicillin
A technologist is reading a Gram stain from a CSF and observes many neutrophils and lancet-shaped gram-positive diplococci. Which set of chemistry and hematology CSF results would most likely be seen in someone with this type of infection? A WBC: Increase Glucose: Increased Protein: Increased B WBC: Decreased Glucose: Decreased Protein: Decreased C WBC: Increased Glucose: Decreased Protein: Increased D WBC: Decreased Glucose: Increased Protein: Decreased Result A Result B Result C Result D
Result C
259. Which of the following tests is most appropriate for the presumptive identification of Clostridium perfringens?
Reverse CAMP test
27. A former species of Corynebacterium pathogenic for swine, horses, and cattle is also known to cause disease in compromised hosts. This organism when grown on culture media produces pale pink colonies that help to presumptively identify it as
Rhodococcus equi -GPB -pink colonies -unable to ferment carbohydrates
285. Rocky Mountain spotted fever is transmit- ted by the bite of a tick infected with
Rickettsia rickettsii
288. The causative agent of endemic or murine typhus is
Rickettsia typhi (transmitted via rats or rat fleas)
Which of the following is considered a primary drug for the treatment of Mycobacterium tuberculosis? Rifampin Kanamycin Rifabutin Ethionamide
Rifampin
23. The beta-hemolysis produced by group A Streptococcus seen on the surface of a sheep blood agar plate is primarily the result of streptolysin
S -Streptolysin S stable in the presence of O2. -Streptolysin O inactivated by O2.
10. In the CAMP test, a single streak of a beta-hemolytic Streptococcus is placed perpendicular to a streak of beta-lysin-producing Staphylococcus aureus. After incubation, a zone of increased lysis in the shape of an arrowhead is noted; this indicates the presumptive identification of
S. agalactiae
274. The recommended medium for the recovery of Mycoplasma pneumoniae from clinical specimens is
SP4 agar
260. Which of the following tests is most appropriate for the presumptive identification of Peptostreptococcus anaerobius?
SPS disk -12-18 mm zone of inhibition interpreted as a presumptive ID of Peptostreptococcus anaerobius
179. Edwardsiella tarda is occasionally isolated in stool specimens and can biochemically be confused with
Salmonella
195. Reptiles kept as pets are sometimes associated with the transmission of
Salmonella
91. Which of the following organisms would most likely produce the biochemical reactions shown in Color Plate 27?
Salmonella -produces H2S in TSI -lysine + -urease =
167. Which of the following is not urease positive?
Salmonella - urease =, H2S +
186. Chronic carriers, persons who remain infected with an organism for long periods, are typically associated with the dissemination of
Salmonella Typhi
An organism was inoculated to a TSI tube and gave the following reactions: Alkaline slant/acid butt, H₂S, gas produced The organism most likely is: Klebsiella pneumoniae Shigella dysenteriae Salmonella typhimurium Escherichia coli
Salmonella typhimurium
5. Exfoliatin produced by Staphylococcus aureus is responsible for causing
Scalded skin syndrome
40. Which one of the following diseases involves erythrogenic toxin?
Scarlet fever -Group A strep produces erythrogenic toxin and causes scarlet fever.
The mycobacteria that produce a deep yellow or orange pigment both in the dark and light are: Photochromogens Scotochromogens Nonchromogens Rapid growers
Scotochromogens
An Enterococcus isolated from multiple blood cultures in a patient endocarditis should be: Screened for high level aminoglycoside resistance Checked for tolerance Assayed for serum antimicrobial activity Tested for beta-lactamase production
Screened for high level aminoglycoside resistance
83. The Haemophilus influenzae vaccine protects against which serotype?
Serotype b
171. A positive gelatin reaction is characteristic of
Serratia liquefaciens
125. A positive DNase would be seen with
Serratia marcescens Staph aureaus is DNase + too
The stock cultures needed for quality control testing of deoxyribonuclease (DNase) production are: Salmonella typhimurium/Escherichia coli Escherichia coli/Pseudomonas aeruginosa Proteus mirabilis/Escherichia coli Serratia marcescens/Escherichia coli
Serratia marcescens/Escherichia coli
A Gram stain of a nectrotic wound specimen showed large gram-positive bacilli. There was 3+ growth on anaerobic media only, with colonies producing a double zone of hemolysis. To identify the organism, the microbiologist should: Determine if the organism ferments glucose Perform the oxidase test Set up egg yolk agar plate Test for bile tolerance
Set up egg yolk agar plate
When processing throat swabs for a group A Streptococccus culture, the medium of choice is: Sheep blood agar Rabbit blood agar Human blood agar Horse blood agar
Sheep blood agar
88. An organism occasionally misidentified as an enteric pathogen because it produces a large amount of H2S is
Shewanella putrefaciens
Which one of the following genera is among the least biochemically reactive members of the Enterobacteriaceae? Proteus Pseudomonas Citrobacter Shigella
Shigella
126. A negative citrate reaction is characteristic of
Shigella boydii E. coli is citrate = too Many Enterobacteriaceae that are VP + are also citrate +
72. The characteristics of being lactose negative, citrate negative, urease negative, lysine decarboxylase negative, and nonmotile best describe which organism?
Shigella dysenteriae
A TSI tube inoculated with an organism gave the following reactions: Alkaline slant, acid butt, no H₂S, no gas produced This organism is most likely: Yersinia enterocolitica Salmonella typhi Salmonella enteritidis Shigella dysenteriae
Shigella dysenteriae
Tests for beta-lactamase production in Haemophilus influenzae: Are not commercially available Include tests that measure a change to an alkaline pH Should be performed on all blood and CSF isolates Are not valid for any other bacterial species
Should be performed on all blood and CSF isolates
An aspirated specimen of purulent material was obtained from a brain abscess. After 24 hours incubation, pinpoint colonies grew on sheep blood and small, yellowish colonies grew on chocolate. Gram stain of the organism showed gram-negative cocci. Results of carbohydrate degradation studies were as follows: Glucose: acid Maltose: acid Sucrose: acid Lactose: negative Additional testing revealed that the organism was oxidase positive and beta-galactosidase negative. The organism is most likely Neisseria: Meningitidiis Sicca Lactamica Gonorrhoeae
Sicca
Which of the following media can be used to culture Campylobacter jejuni? Skirrow medium CIN agar Anaerobic CNA agar Bismuth sulfite
Skirrow medium
331. The recommended anticoagulant for use when a body fluid or joint fluid that may clot is sent for microbiologic examination is
Sodium polyethanolsulfonate (SPS)
Biochemical reactions of an organism are consistent with Shigella. A suspension is tested in antiserum without resulting agglutination. However, after 15 minutes of boiling, agglutination occurs in group D antisera. The Shigella species is: Dysenteriae Flexneri Boydii Sonnei
Sonnei
MacConkey media for screening suspected cases of hemorrhagic E coli O157:H7 must contain: Indole Citrate Sorbitol Lactose
Sorbitol
299. Which of the following is not correct regarding spirochetes?
Spirochetes are gram positive.
Which of the following is a dimorphic fungus? Sporothrix schenckii Candida albicans Cryptococcus neoformans Aspergillus fumigatus
Sporothrix schenckii
224. Which of the following specimens is routinely decontaminated when trying to recover Mycobacterium spp.?
Sputum
286. Transmission of the sylvatic form of typhus infection caused by Rickettsia prowazekii is associated with
Squirrels Flying squirrels (Glaucomys volans) transmit the sylvatic form of typhus.
54. Which of the following is most likely to be isolated in cultures from the anterior nares of healthcare workers?
Staphylococcus aureus
57. Family members attending a picnic became ill about 2 hours after eating. The illness was characterized by rapid onset of violent vomiting. The most likely bacterial cause of such symptoms would be food poisoning caused by
Staphylococcus aureus
60. The etiologic agent of the majority of adult joint infections is
Staphylococcus aureus
64. An infant was hospitalized with a severe, tender erythema. The child's epidermis was loose, and large areas of skin could be peeled off. The condition described is most consistent with a clinical syndrome associated with
Staphylococcus aureus
Production of beta-lactamase is inducible in which of the following: Haemophilus influenzae Staphylococcus aureus Corynebacterium diphtheriae Streptococcus pyogenes
Staphylococcus aureus
Of the following bactera, the most frequent cause of prosthetic heart valve infections occurring within 2-3 months after surgery is: Streptococcus pneumoniae Streptococcus pyogenes Staphylococcus aureus Staphylococcus epidermidis
Staphylococcus epidermidis
52. The most common etiologic agent of infections associated with the surgical insertion of prosthetic devices such as artificial heart valves and cerebrospinal fluid shunts is
Staphylococcus epidermidis -coagulase negative
324. Which of the following is not one of the standard control organisms used for the weekly testing of antimicrobial disks?
Staphylococcus epidermidis (ATCC 25833)
345. Which of the following would not be appropriate for a positive control in the PYR test?
Staphylococcus lugdunensis Staphylococcus aureus is + and Staphylococcus lugdunensis is =
44. A urine culture from a 23-year-old female grew a catalase-positive gram-positive coccus ( > 100,000 cfu/mL), which would most likely be
Staphylococcus saprophyticus -nonhemolytic -coagulase = -resistant to novobiocin
58. The novobiocin susceptibility test is used for the identification of
Staphylococcus saprophyticus - usually resistant
68. The enterotoxins of both Vibrio cholerae O1 and noninvasive (toxigenic) strains of Escherichia coli produce serious diarrhea by what mechanism?
Stimulation of adenylate cyclase, which gives rise to excessive fluid secretion by the cells of the small intestine
A gram-positive coccus isolated from a blood culture has the following characteristics: Optochin susceptibility: Negative Bacitracin (0.04 ∪) susceptibility: Negative Bile esculin hydrolysis: Negative Hippurate hydrolysis: Positive Catalase: Negative The organism is most likely: Staphyloccous aureus Streptococcus pneumoniae Streptococcus pyogenes Streptococcus agalactiae
Streptococcus agalactiae
51. Colonies of Listeria monocytogenes on a sheep blood agar plate most closely resemble colonies of
Streptococcus agalactiae -Listeria monocytogenes: small GPB motile at room temp; beta hemolytic on SBA; catalase + while Strep. agalactiae is catalase =
35. Which of the following organisms is able to hydrolyze sodium hippurate to benzoic acid and glycine?
Streptococcus agalactiae (group B strep) -use ninhydrin to detect
13. The etiologic agent most commonly associated with septicemia and meningitis of newborns is
Streptococcus agalactiae (strep group B) -normal flora of the vagina
The optochin (erythlhydrocupreine hydrochloride) disk is used for the identification of: Haemophilus influenzae Group A beta-hemolytic streptococci Streptococcus pneumoniae Alpha-hemolytic stretococci
Streptococcus pneumoniae
43. Rust-colored sputum in cases of lobar pneumonia is characteristic of which of the following possible etiologic agents?
Streptococcus pneumoniae -patients with lobal pneumonia produce rust-colored, blood-tinged sputum -Gram+ lanceolate, alpha hemolytic
55. Ethylhydrocupreine HCl (optochin) susceptibility is a presumptive test for the identification of
Streptococcus pneumoniae Optochin differentiates S. pneumoniae from viridans Strep: S. pneumo is susceptible, viridans strep is resistant.
56. Solubility in the presence of sodium desoxycholate is characteristic of
Streptococcus pneumoniae S. pneumoniae colonies dissolve; viridans strep colonies remain intact.
41. Cultures of the posterior pharynx are most commonly submitted to the clinical laboratory for the detection of
Streptococcus pyogenes
An important cause of acute exudative pharyngitis is: Staphylococcus aureus (beta-hemolytic) Streptococcus penumoniae Streptococcus agalactiae Streptococcus pyogenes
Streptococcus pyogenes
Which of the following organisms is, to date, considered universally susceptible to penicillin: Haemophilus influenzae Neisseria gonorrhoeae Streptococcus pyogenes Corynebacterium diphtheriae
Streptococcus pyogenes
18. The etiologic agent of the disease erysipelas is
Streptococcus pyogenes -Erysipelas results from person-to-person transmission of group A strep. -Erysipelothrix rhysiopathie causes ERYSIPELOID.
33. A child presented in August at the pediatric clinic with a superficial skin infection of the neck. The large, itchy lesions were cultured, and the diagnosis of impetigo was made. One of the etiologic agents of this clinical condition is
Streptococcus pyogenes -S. aureus causes the bullous form of impetigo; S. pyogenes causes the thick crust form of impetigo.
304. Which of the following organisms would not routinely undergo antimicrobial susceptibiity testing?
Streptococcus pyogenes (group A strep) Also, streptococcus agalactiae (group B strep) and Neisseria meningitidis.
Which of the following organisms does not require susceptibility testing to the antimicrobial indicated when isolated from a clinically significant source? Staphylococcus aureus - clindamycin Proteus mirabilis - gentamicin Streptococcus pyogenes - penicillin Escherichia coli - levofloxacin
Streptococcus pyogenes - penicillin
42. Streptococcus sanguis, a viridans streptococcus, is most commonly associated with which of the following clinical conditions?
Subacute bacterial endocarditis
303. The chemotherapeutic agents structurally similar to the vitamin p-aminobenzoic acid that act by inhibiting bacteria via inhibition of folic acid synthesis are
Sulfonamides (interfere with the bacteria's ability to use p-aminobenzoic acid, which is part of the folic acid molecule; bacteriostatic and not bactericidal)
250. Which of the following organisms is not gram-positive?
Suttonella wadsworthensis -anaerobic, GNB
308. The term that denotes a situation in which the effect of two antimicrobial agents together is greater than the sum of the effects of either drug alone is
Synergism A tenfold decrease in the number of viable cells from that obtained by the most effective drug in the combination is the definition of synergism.
291. Detection of antibody against cardiolipin is useful for the diagnosis of which of the following diseases?
Syphilis Cardiolipin antibodies are detected by the RPR and VDRL tests.
The causative agent for cysticercosis is: Taenia solium Taenia saginata Ascaris lumbricoides Trichuris trichuria
Taenia solium
The laboratory receives a blood culture from a veterinarian who has been ill for many weeks with fevers in the afternoon and evenings, arthritis, and fatigue. The blood culture is positive after 5 days, and the organism has the following characteristics: Gram stain: small, gram-negative coccobacilli Sheep blood agar: growth after 48 hours with small, smooth, raised colonies What should the microbiologist do next? Consider the growth contamination and perform another gram stain Perform biochemical identification for HACEK organisms Perform identification and susceptibility testing using an automated system Take extra safety precautions for possible Brucella
Take extra safety precautions for possible Brucella
300. A positive VDRL test for syphilis was reported on a young woman known to have hepatitis. When questioned by her physician, she denied sexual contact with any partner symptomatic for a sexually transmitted disease. Which of the following would be the appropriate next step for her physician?
Test her serum using a fluorescent treponemal antibody-absorbed assay
All species of the genus Neisseria have the enzyme to oxidize: Naphthylamine Dimethylaminobenzaldehyde Glucopyranoside Tetramethyl-phenylenediamine
Tetramethyl-phenylenediamine
A control stain of Clostridium should be used an anaerobe jar to assure: That plate media is working That an anaerobic environment is achieved That the jar is filled with a sufficient number of plates That the indicator strip is checked
That an anaerobic environment is achieved
Susceptibility tsting is performed on a Staphylococcus aureus isolate from a blood culture with the following results: Oxacillin: Resisitant Cefazolin: Susceptible Clindamycin: Susceptible Erythromycin: Susceptible Trimethoprim/Sulfamethoxazole: Susceptible Vancomycin: Susceptible What should the technologist do next? Ceftraixone should be reported instead of cefazolin Clindamycin should be tested for inducible resistance prior to reporting The trimethoprim/sulfamethoxazole result should be removed since all S aureus are resistant The cefazolin result should be changed to resistant since the oxacillin result is resistant
The cefazolin result should be changed to resistant since the oxacillin result is resistant
The susceptibility results below are reported on an Enterococcus faecalis isolated from peritoneal fluid. Ampicillin: susceptible Vancomyin: resistant Clindamycin: susceptible Levofloxacin: resistant Linezolid: susceptible The physician calls questioning the results. Which of the following should have been done before the report was released? The clindamycin results should have been removed from the report since it is inactie against Enterococcus The ampicillin result whould have been changed to resistant since the isolate is vancomycin resistant The linezolid result should have been removed from the report since it is inactive against Enterococcus Ciprofloxacin should have been added to the report since levofloxacin was resistant
The clindamycin result should have been removed from the report since it is inactive against Enterococcus
Susceptibility testing performed on quality control organisms using a new media lot number yielded zone sizes that were too large for all antibiotics tested. The testing was repeated using media from a previously used lot number, and all zone sizes were acceptable. Which of the following best explains the unacceptable zone sizes? The antibiotic disks were not stored with the proper desiccant The depth of the media was too thick The depth of the media was too thin The antibiotic disks were not properly applied to the media
The depth of the media was too thin
192. When performing the oxidase test, which of the following would not be appropriate?
The reagent used is o-nitrophenyl-beta-D-galactopyranoside.
109. Which of the following statements is not true of Brucella?
The risk of accidental laboratory infection is no greater than with any other organism.
Upon review of a sputum Gram stain, the technician notes that the nuclei of all the neutrophils present in the smear are staining dark blue. The best explanation for this finding is: The slide was inadequately decolorized with acetone/alcohol The sputum smear was prepared too thin The cellular componenets have stained as expected The iodine was omitted from the staining procedure
The slide was inadequately decolorized with acetone/alcohol
Which of the following is the most important variable in the recovery of organisms in patients with bacteremia? Subculture of all bottles at day 5 of incubation The volume of blood cultured Use of chlorhexadine for skin antisepsis Collection of multiple blood culture sets from a single venipuncture
The volume of blood cultured
During the past month, Staphylococcus epidermidis has been isolated from the blood cultures at 2-3 times the rate of the previous year. The most logical explanation for the increase in these isolates is that: The blood culture media are contaminated with this organism the hospital ventialtion system is contaminated with Staphyloccus epidermidis There has been a break in proper skin preparation before drawing blood for culture A relatively virulent isolate is being spread from patient to patient
There has been a break in proper skin preparation before drawing blood for culture
Anaerobic infections differ from aerobic infections in which of the following? They usually respond favorably with aminoglycoside therapy They usually arise from exogenous sources They are usually polymicrobic Gram stains of specimens are less helpful in diagnosis
They are usually polymicrobic
Vibrio parahaemolyticus can be isolated best from feces on: Eosin methylene blue (EMB) agar Hektoen enteric (HE) agar Salmonella Shigella (SS) agar Thiosulfate citrate bile salts (TCBS) agar
Thiosulfate citrate bile salts (TCBS) agar
A community hospital microbiology laboratory is processing significant numbers of stool cultures because of an outbreak of diarrhea following heavy rains and flooding in the county. A media that should be incorporated in the plating protocol is: Colistin nalidixic acid for Listeria MacConkey agar with sorbitol for Campylobacter Mannitol salt agar for Enterococcus species Thiosulfate citrate bile salts sucrose for Vibrio species
Thiosulfate citrate bile salts sucrose for Vibrio species
191. For the selective isolation of Vibrio spp. the recommended agar is
Thiosulfate-citrate-bile salt-sucrose agar
313. An example of a bactericidal antibiotic is
Tobramycin Bactericidal antibiotics actually destroy the bacteria, but bacteriostatic drugs only arrest the growth of the microorganism.
317. The phenomenon of bacterial resistance to the bactericidal activity of penicillins and cephalosporins,with only inhibition of the organism's growth, is known as
Tolerance
Which of the following factors would make an organism appear to be more resistant on a disk diffusion susceptibility test? Too little agar in the plate Too many organisms on the inoculum The presence of 0.5% NaCl in the medium A medium with a pH of 7.4
Too many organisms on the inoculum
352. A young woman complaining of symptoms of sudden onset of fever, vomiting, diarrhea, and rash was seen by her gynecologist. She was admitted to the hospital, where a culture of vaginal discharge grew many coagulase-positive staphylococci. The most likely diagnosis in this case would be
Toxic shock syndrome
Multifocal brain lesion in AIDS patients is commonly caused by: Toxoplasma gondii Pneumocytis jiroveci Cryptosporidium parvum Gardia lamblia
Toxoplasma gondii
293. Serious congenital infections are associated with
Treponema pallidum subsp. pallidum -causes syphilis which can be transmitted to a fetus if the pregnant woman has septicemia
When performing a Kovac indole test, the substrate must contain: Indole Tryptophan Ornithine Paradimethylaminobenzaldehyde
Tryptophan
A stool specimen for ova and parasite examination contained numerous rhabditiform larvae. Which factor does not aid in the identification of larvae? Larva tail morphology Type of water vegetation consumed Length of the buccal cavity Appearance of the geinatl primordium
Type of water vegetation consumed
A gastroenterologist submits a gastric biopsy from a patient with a peptic ulcer. To obtain presumptive evidence of Helicobacter pylori, a portion of the specimen should be added to which media? Urea broth Tetrathionate Selenite Tryptophan
Urea broth
121. Yersinia pestis is characteristically
Urease negative Y. pestis causes plague. Transmitted by rat flea. Oxidase =, nonmotile at 20-25°C, urease =, H2S =
Chlamydial infections have been implicated in: Urethritis and conjunctivitis Gastroenteritis and urethritis Neonatal pneumonia and gastroenteritis Neonatal meningitis and conjunctivitis
Urethritis and conjunctivitis
11. Staphylococcus saprophyticus, a recognized pathogen, is a cause of
Urinary tract infections -Staph saprophyticus is coagulase = and is resistant to novobiocin.
Which one of the following specimen requests is acceptable? Feces submitted for anaerobic culture Foley catheter tip submitted for aerobic culture rectal swab submitted for direct smear for gonococci Urine for culture of acid-fast bacilli
Urine for culture of acid-fast bacilli
The procedure that assures the most accurate detection of mecA-mediated oxacillin resistance in routine broth micro dilution susceptibility testing against S aureus is: Addition of 4% NaCl Incubation at 30°C Incubation for 48 hours Use of cefoxitin for testing
Use of cefoxitin for testing
When using a control strain of Staphylococcus aureus, the technologist notices that the zone around the oxacillin disk is too small. Which of the following is the most likely explanation? Inoculation of the plates 10 minutes after preparing the inoculum Incubation of the Mueller-Hinton plates at 35°C Use of a 0.25 McFarland standard to prepare inoculum Use of outdates oxacillin disks
Use of outdated oxacillin disks
The steam autoclave method of sterilization: Uses 15 lbs of pressure for 15 minutes Utilizes dry heat for 20 minutes Produces a maximum temperature of 100°C Requires a source of ethylene oxide
Uses 15 lbs of pressure for 15 minutes
The ability to detect oxacillin-resistant Staphylococcus aureus may be enhanced by: Shortening incubation of standard susceptibility plates Incubating susceptibility plates at 39-41°C using Mueller-Hinton broth with 2% NaCl Adjusting inoculum to 0.1 McFarland before inoculating susceptibility plates
Using Mueller-Hinton broth with 2% NaCl
81. The species of Vibrio closely associated with rapidly progressing wound infections seen in patients with underlying liver disease is
V. vulnificus
320. Which of the following antimicrobial agents acts by inhibiting cell wall synthesis?
Vancomycin
When performing a stool culture, a colony type typical of an enteric pathogen is subcultured on a blood agar plate. The resulting pure culture is screened with several tests to obtain the following results: TSI: acid butt, alkaline slant, no gas, no H2S phenylalanine deaminase: neg Motility: pos Serological typing: Shigella flexneri (Shigella subgroup B) The serological typing is verified with new kit and controls. The best course of action would be to: Report the organism of Shigella flexneri without further testing Verify reactivity of motility medium with positive and negative controls Verify reactivity of the TSi slants with positive and negative controls for H₂S production Verify reactivity of phenylalanine deaminase with positive and negative controls
Verify reactivity of motility medium with positive and negative controls
74. Fecal cultures are inoculated on thiosulfate-citrate-bile salts-sucrose agar specifically for the isolation of
Vibrio -If the species ferments sucrose, it produces yellow colonies. If not, it produces green colonies.
107. The symptom of diffuse, watery diarrhea that produces a relatively clear stool containing mucus flecks is suggestive of an infection caused by
Vibrio cholerae
108. An example of a halophilic microorganism is
Vibrio parahaemolyticus Halophilic - requires increased osmotic pressure in the form of salt for growth.
112. Explosive watery diarrhea with severe abdominal pain after eating raw shellfish is most characteristic of infection caused by
Vibrio parahemolyticus
349. A 45-year-old man was seen in the emergency department with fever, chills, nausea, and myalgia. He reported that 2 days earlier he had eaten raw oysters at a popular seafood restaurant. On admission he was febrile and had hemorrhagic, fluid- filled bullous lesions on his left leg. The patient had a history of diabetes mellitus, chronic hepatitis B, and heavy alcohol consumption. The patient, who had a temperature of 102.2°F, was admitted to the intensive care unit for presumed sepsis, and treatment was begun. A curved gram- negative rod was isolated from blood cultures drawn on admission and fluid from the bullous leg wound. On the third day, disseminated intravascular coagulation developed, and he died. The source of the oysters eaten by the deceased patient was the Gulf of Mexico. The most likely etiologic agent in this case would be
Vibrio vulnificus
31. A negative PYR (L-pyrolidonyl-a- naphthylamide) test is demonstrated by
Viridans streptococci -PYR positive: group A strep, Enterococcus, Micrococcus, and Lactococcus
20. A common member of the normal flora of the upper respiratory tract is
Viridans streptococcus -most common normal flora in upper resp. cultures. -opportunistic with low virulence
46. The pulmonary form of anthrax is known as
Woolsorters disease -transmitted through inhalation
135. Vibrio vulnificus is a well-established human pathogen that is known to cause
Wound infections Vibrio vulnificus - halophilic lactose-fermenting
353. A 32-year-old male was seen in the emergency department with symptoms of lower right quadrant abdominal pain and diarrhea. A complete blood count showed a leukocytosis with an increased number of neutrophils. He was admitted, and a stool culture was obtained. The culture showed many gram-negative bacilli, which were oxidase negative, citrate negative, and indole negative. The triple sugar iron reaction was acid over acid, but there was no evidence of gas or H2S production. The organism was positive for urease and ONPG and negative for phenylalanine. The characteristic symptomatology and the biochemical reactions confirmed that the etiologic agent was
Yersinia enterocolitica
An isolate from a stool culture gives the following growth characteristics and biochemical reactions: MacConkey agar: colorless colonies Hektoen agar: yellow-orange colonies TSI: acid slant/acid butt, no gas, no H₂S Urea: positive These screening reactions are consistent with which of the following enteric pathogens? Yersinia enterocolitica Shigella sonnei Vibrio parahaemolyticus Campylobacter jejuni
Yersinia enterocolitica
Which one of the following gram-negative bacilli ferments glucose? Alcaligenes faecalis Pseudomonas cepacia Acinetobacter lwoffii Yersinia enterocolitica
Yersinia enterocolitica
356. An anemic patient was transfused with packed red blood cells. Approximately 1 hour after the transfusion began, the patient developed fever and hypotension consistent with endotoxic shock. The red blood cells had been stored at 4°C for approximately 30 days before their use. The organism most likely to be involved in this case is
Yersinia enterocolitica (can survive at 4°C inside RBCs without causing RBC lysis)
160. Cefsulodin-irgasan-novobiocin (CIN) agar is recommended for the recovery of
Yersinia enterocolitica - "bulls eye" colonies
Which of the following is the MOST appropriate organism and media combination? Legionella species - Regan Lowe Clostridium difficile - Phenylethyl alcohol (PEA) Campylobacter species - Charcoal yeast extract Yersinia enterocolitica - Cefsulodin-irgasan-novobiocin (CIN)
Yersinia enterocolitica - cefsulodin-irgasan-novobiocin (CIN)
A 25-year-old man who had recently worked as a steward on a transoceanic grain ship presented to the emergency room with high fever, diarrhea and prostration. Axillary lymph nodes were hemorrhagic and enlarged. A Wayson stain of the aspirate showed bacilli that were bipolar, resembling safety pins. The most likely identification of this organism is: Brucella melitensis Streptobacillus moniliformis Spirillum minus Yersinia pestis
Yersinia pestis
In a disk diffusion susceptibility test, which of the following can result if disks are placed on the inoculated media and left at room temperature for an hour before incubation? The antibiotic would not diffuse into the medium, resulting in no zone Zones of smaller diameter would result Zones of larger diameter would result There would be no effect on the final zone diameter
Zones of larger diameter will result
On day 3 of a fungal culture, grayish cottony growth is observed that is filling the container. The most likely mold isolated is a: Dermatophyte Dimorphic mold Zygomycete Dematiaceous mold
Zygomycete
97. The single species in the genus Hafnia is
alvei -positive for motility, lysine, ornithine, ONPG, and KCN reactions.
98. Acinetobacter baumannii
is oxidase negative grow on most lab plates, nonfermenters
