Intern quizzes and exams
Staphylococcus aureus recovered from a wound culture gave the following antibiotic sensitivity pattern by the standardized Kirby-Bauer method (S = sensitive; R = resistant): Penicillin = R Ampicillin = S Cephalothin = R Cefoxitin = R Vancomycin = S Methicillin = R Which is the drug of choice for treating this infection? Vancomycin Cephalothin Penicillin Ampicillin
Vancomycin
Which selective medium is used for the isolation of gram-positive microorganisms? Trypticase soy agar with 5% sheep blood Eosin methylene blue Columbia CNA with 5% sheep blood Modified Thayer-Martin
Columbia CNA with 5% sheep blood
What is the name of the group of bacteria that are slightly curved, gram-positive rods often referred to asclub-shaped or Chinese letters when viewed in a Gram stain? Listeria Corynebacterium Staphylococcus Neisseria
Corynebacterium
What are two tests presumptively used to identify group B strep? PYR and hippurate hydrolysis Hippurate hydrolysis and CAMP Optochin and PYR Bacitracin and PYR
Hippurate hydrolysis and CAMP
The drugs of choice for treatment of infections with Enterobacteriaceae are: Chloramphenicol, ampicillin, and colistin Streptomycin and isoniazid (isonicotinylhydrazide [INH]) Aminoglycosides, sulfamethoxazole-trimethoprim, third-generation cephalosporins Ampicillin and nalidixic acid
Aminoglycosides, sulfamethoxazole-trimethoprim, third-generation cephalosporins
In the test for urease production, ammonia reacts to form which product? Ammonium citrate Ammonium carbonate Ammonium oxalate Ammonium nitrate
Ammonium carbonate
A fourfold rise in titer of which antibody is the best indicator of a recent infection with group A β-hemolytic streptococci? Anti-streptolysin O Anti-streptolysin S Anti-M Anti-A
Anti-streptolysin O
The catalase test for mycobacteria differs from that used for other types of bacteria by using: 3% H2O2 and phosphate buffer, pH 6.8 10% H2O2 and 0.85% saline 30% H2O2 and 10% Tween 80 1% H2O2 and 10% Tween 80
30% H2O2 and 10% Tween 80
What temperature is an optimal growth temperature for Campylobacter jejuni? 42° C 60° C 35° C 25° C
42° C
The aseptic collection of blood cultures requires that the skin be cleansed with: 95% alcohol only 2% iodine and then 70% alcohol solution 70% alcohol and then 95% alcohol 70% alcohol and then 2% iodine or an iodophor
70% alcohol and then 2% iodine or an iodophor
An immunocompromised patient was admitted to the hospital with a diagnosis of hemorrhagic cystitis. Which combination of virus and specimen would be most appropriate to diagnose a viral cause of this disorder? Human papilloma virus-skin BK virus-urine Hepatitis B virus-serum Epstein-Barr virus-serum
BK virus-urine
What bacterium produces colonies that are nonhemolytic, large, gray, and flat with an irregular margin on sheep blood agar (SBA)? Bacillus anthracis Nocardia asteroides Listeria monocytogenes Streptococcus pneumoniae
Bacillus anthracis
Large, gram-positive, spore-forming rods growing on blood agar as large, raised, β-hemolytic colonies that spread and appear as frosted green-gray glass are most likely: Pseudomonas spp. Bacillus spp. Corynebacterium spp. Listeria spp.
Bacillus spp.
Which of the following organisms usually grow on kanamycin, vancomycin, laked blood agar? Porphyromonas and Enterococcus Mobiluncus and Gardnerella Salmonella and Shigella Bacteroides and Prevotella
Bacteroides and Prevotella
A gram-negative coccobacillus was recovered on chocolate agar from the CSF of an immunosuppressed patient. The organism was nonmotile and positive for indophenol oxidase but failed to grow on MacConkey agar. The organism was highly susceptible to penicillin. The most probable identification is: Pseudomonas aeruginosa Moraxella lacunata Pseudomonas stutzeri Acinetobacter spp.
Moraxella lacunata
Which genera are positive for phenylalanine deaminase? Klebsiella and Enterobacter Proteus, Escherichia, and Shigella Morganella, Providencia, and Proteus Enterobacter, Escherichia, and Salmonella
Morganella, Providencia, and Proteus
The best procedure to differentiate Listeria monocytogenes from Corynebacterium is: Catalase Gram stain Motility at 35°C Motility at 25°C
Motility at 25°C
A Mycobacterium species recovered from a patient with AIDS gave the following results: Niacin = Neg Tween 80 hydrolysis = Neg Heat-stable catalase (68°C) = ± Nonphotochromogen T2H = + Nitrate reduction = Neg What is the most likely identification? Mycobacterium avium complex Mycobacterium gordonae Mycobacterium kansasii Mycobacterium bovis
Mycobacterium avium complex
How is cholera treated? Tetracycline Copious amounts of intravenous fluids Aminoglycosides with a large amount of intravenous fluids Rest and cold showers
Copious amounts of intravenous fluids
A positive India ink test is usually presumptive for: Histoplasma capsulatum Candida albicans Candida glabrata Cryptococcus neoformans
Cryptococcus neoformans
All of the following are appropriate when attempting to isolate N. gonorrhoeae from a genital specimen except: Plate the specimen directly on modified Thayer-Martin (MTM) medium Transport the genital swab in charcoal transport medium Culture specimens in ambient oxygen at 37°C Plate the specimen directly on New York City or Martin-Lewis agar
Culture specimens in ambient oxygen at 37°C
Autofluorescence requires no stain and is recommended for the presumptive identification of: Entamoeba histolytica cysts Toxoplasma gondii tachyzoites Cyclospora cayetanensis oocysts Dientamoeba fragilis trophozoites
Cyclospora cayetanensis oocysts
The following characteristics of an obligate anaerobic gram-negative bacilli best describe which of the listed genera? Gram staining = Long, slender rods with pointed ends Colonial appearance = Dry bread crumbs or "fried-egg" appearance Penicillin two-unit disk test = Susceptible Fusobacterium spp. Bacteroides spp. Prevotella spp. Porphyromonas spp.
Fusobacterium spp.
"Clue cells" are seen on a smear of vaginal discharge obtained from an 18-year-old female emergency department patient. This finding, along with a fishy odor (amine) after the addition of 10% KOH, suggests bacterial vaginosis caused by which organism? Staphylococcus epidermidis Streptococcus agalactiae Gardnerella vaginalis Escherichia coli
Gardnerella vaginalis
A 25-year-old pregnant patient complained of vaginal irritation. Cultures taken for STDs proved negative. The Gram-stained vaginal smear revealed many epithelial cells with gram-variable short rods (coccobacilli) covering the margins. What is the most likely cause of the vaginosis? Staphylococcus aureus Staphylococcus saprophyticus Gardnerella vaginalis Group B streptococci
Gardnerella vaginalis
Methods other than packaged microsystems used to identify anaerobes include: Special staining Enzyme immunoassay Gas-liquid chromatography (GLC) Antimicrobial susceptibility testing
Gas-liquid chromatography (GLC)
Fecal immunoassays have become more commonly used to diagnose infections with: Endolimax nana and Blastocystis spp. Giardia lamblia (G. intestinalis, G. duodenalis) and Cryptosporidium spp. Ascaris lumbricoides and Trichuris trichiura Strongyloides stercoralis and Trichomonas vaginalis
Giardia lamblia (G. intestinalis, G. duodenalis) and Cryptosporidium spp.
Which group of β-hemolytic streptococci is associated with erythrogenic toxin production? Group G Group B Group C Group A
Group A
Alternaria and Curvularia can be differentiated based on: Clinical history biochemical profile growth rate Microscopic appearance of macroconidia
Microscopic appearance of macroconidia
A Gram stain performed on a sputum specimen revealed gram-negative diplococci within neutrophils. Oxidase testing is positive and carbohydrate degradation tests are inert. The organism is: Moraxella catarrhalis Neisseria lactamica Neisseria meningitidis Neisseria sicca
Moraxella catarrhalis
A lymph node biopsy specimen obtained from a 30-year-old male patient was submitted to the microbiology laboratory for culture and AFB smear for mycobacteria. The specimen was fixed in formalin. This specimen should be: Cultured for anaerobes only Held at room temperature for 24 hours and then cultured Accepted for AFB smear preparation and cultured Rejected
Rejected
A 13-year-old boy was admitted to the hospital with a diagnosis of viral encephalitis. History revealed that the boy harbored wild raccoons from nearby woods. What is the best method to determine if the boy has contracted rabies? . Request immunofluorescent test for antigen in cutaneous nerve specimen obtained by nuchal biopsy Request immunofluorescent test for antibody on the saliva from all of the raccoons Remove the brainstems from all of the raccoons and examine for cytopathic effects Isolate the virus from the saliva of both the animals and the patient
Request immunofluorescent test for antigen in cutaneous nerve specimen obtained by nuchal biopsy
Lysine iron agar (LIA) showing a purple slant and a blackened butt indicates: Escherichia coli Citrobacter spp. Salmonella spp. Proteus spp.
Salmonella spp
Which of the following motile trophozoites may be observed in urine? All of these options Schistosoma haematobium Trichomonas vaginalis Giardia lamblia
Trichomonas vaginalis
Which of the following clean catch urine culture colony counts indicates the patient likely has a urinary tract infection? 105 CFU/mL 103 CFU/mL 101 CFU/mL No growth
103 CFU/mL
Under what conditions should inoculated plates for Neisseria gonorrhoeae culture be incubated? 35° C and room air 25° C and room air 25° C and 3% to 5% carbon dioxide 35° C and 3% to 5% carbon dioxide
35° C and 3% to 5% carbon dioxide
Most bacterial cultures are incubated at what temperature range? 40°C to 42°C 30°C to 40°C 25°C to 27°C 35°C to 37°C
35°C to 37°C
Staphylococcus saprophyticus is best differentiated from Staphylococcus epidermidis by resistance to: 5 µg of novobiocin 5 µg of lysostaphin 0.04 unit of bacitracin 10 units of penicillin
5 µg of novobiocin
The normal amount of blood in blood agar plates is: 5% 10% 1.5% 2%
5%
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? 700 70,000 7,000 70
70,000
What media does Corynebacterium diphtheriae grow on? Cystine-tellurite blood Loeffler medium Sheep blood agar (SBA) All of these options
All of these options
The ONPG test allows organisms to be classified as lactose fermenters by testing for which of the following? Beta-galactosidase Beta-lactamase Phosphatase Permease
Beta-galactosidase
Physiologic classification of streptococci divide the species into all the following groups except: Enterococci Lactococci Pyogenic streptococci Beta-hemolytic streptococci
Beta-hemolytic streptococci
What two tests are presumptively used to identifyEnterococcus? Bacitracin and PYR Catalase and coagulase Bile esculin and 6.5% NaCl broth PYR and hippurate hydrolysis
Bile esculin and 6.5% NaCl broth
Which test is used to differentiate the viridans streptococci from the group D streptococci and enterococci? Bacitracin disk test CAMP test Hippurate hydrolysis test Bile esculin test
Bile esculin test
What test differentiates staphylococci from streptococci? Coagulase All of these options Beta-hemolysis Catalase
Catalase
Gram stain examination from a blood culture bottle shows dark blue, spherical organisms in clusters. Growth on sheep blood agar shows small, round, pale yellow colonies. Further tests should include: Oxidase and deoxyribonuclease reactions Catalase production and coagulase test Vogues-Proskauer and methyl red reactions Bacitracin susceptibility and serological typing
Catalase production and coagulase test
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: Chopped meat glucose Blood agar Chocolate agar plate Thayer-Martin plate
Chocolate agar plate
Proper media for culture of a urethral discharge from a man include: Sheep blood and phenylethyl alcohol agars Eosin-methylene blue and sheep blood agars Chocolate and modified Thayer-Martin agars Thioglycollate broth and chocolate agar
Chocolate and modified Thayer-Martin agars
A reliable test for distinguishing Staphylococcus aureus from other staphylococci is: Optochin susceptibility Oxidase Coagulase Catalase
Coagulase
The correct order of reagents in a gram stain is: Safranin, iodine, acetone/alcohol, crystal violet Crystal violet, iodine, acetone/alcohol, safranin Iodine, acetone/alcohol, crystal violet, safranin Safranin, acetone/alcohol, crystal violet, iodine
Crystal violet, iodine, acetone/alcohol, safranin
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 Reconfirm the hemolytic reaction on a fresh 24-hour culture Report a coagulase-negative Staphylococcus aureus Do a tube coagulase test to confirm the slide test
Do a tube coagulase test to confirm the slide test
What test is performed to determine if Corynebacterium diphtheriae is a toxigenic strain of an organism? Elek test Lancefield group test Schick test Coagulase
Elek test
All of the following virulence factors are associated with Staphylococcus aureus except: Cytolytic toxins Endotoxins Enterotoxins Cellular components such as protein A
Endotoxins
Micrococcus and Staphylococcus species are differentiated by which test(s)? All of these options Catalase test Fermentation of glucose (OF) tube Gram stain
Fermentation of glucose (OF) tube
What organism presents as a pink colony with a halo on MacConkey media and a green metallic sheen on eosin methylene blue (EMB)? Klebsiella pneumonia Escherichia coli Salmonella enterica Proteus mirabilis
Escherichia coli
Which genera of the Enterobacteriaceae are known to cause diarrhea and are considered enteric pathogens? Enterobacter, Klebsiella, Providencia, and Proteus Pseudomonas, Moraxella, Acinetobacter, and Aeromonas Escherichia, Salmonella, Shigella, and Yersinia Enterobacter, Citrobacter, and Morganella
Escherichia, Salmonella, Shigella, and Yersinia
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 the organism is: Nonfermenter Obligate anaerobe Facultative anaerobe Aerobe
Facultative anaerobe
Streptococcus exhibit which of the following properties? May be α-, β-, or γ-hemolytic, and catalase positive Facultative anaerobe, β-hemolytic, catalase positive Aerobic, oxidase positive, and catalase positive Facultative anaerobe, oxidase negative, catalase negative
Facultative anaerobe, oxidase negative, catalase negative
Biochemically, the Enterobacteriaceae are gram-negative rods that: Ferment glucose, produce indophenol oxidase, and form gas Ferment lactose, produce indophenol oxidase, and form gas Ferment glucose, reduce nitrate to nitrite, and are oxidase negative Ferment lactose and produce indophenol oxidase
Ferment glucose, reduce nitrate to nitrite, and are oxidase negative
Staphylococci are gram-positive arranged in pairs or clusters, while streptococci are: Gram-negative arranged in pairs or clusters Gram-positive arranged in pairs or clusters too Gram-negative arranged in pairs or chains Gram-positive arranged in pairs or chains
Gram-positive arranged in pairs or chains
A β-hemolytic streptococci that is bacitracin-sensitive and CAMP-negative is: Group A Beta-hemolytic, not group A, B, or D Beta-hemolytic, group D Group B
Group A
The L-pyrrolidonyl-β-naphtylamide (PYR) hydrolysis test is a presumptive test for which streptococci? Nongroup A or B β-hemolytic streptococci Group A and D (enterococcus) streptococci Group A and B β-hemolytic streptococci Streptococcus pneumoniae and group D streptococci (nonenterococcus)
Group A and D (enterococcus) streptococci
According to the Lancefield classification, Streptococcus agalactiae is referred to as: Group A streptococci Group B streptococci Group D streptococci Group C streptococci
Group B streptococci
Which Haemophilus is difficult to isolate and recover from genital ulcers and swollen lymph nodes? H. haemolyticus H. ducreyi H. parahaemolyticus H. aphrophilus
H. ducreyi
An isolate in chocolate agar from a patient with epiglottitis was suggestive of Haemophilus Additional testing showed that the isolate required NAD for growth and was nonhemolytic. The organism is most likely: H. ducreyi H. influenzae H. parainfluenzae H. haemolyticus
H. influenzae
Which species ofHaemophilus requires both X and V factors? H. paraphrophilus H. parainfluenzae H. aphrophilus H. influenzae
H. influenzae
Nutritionally deficient streptococci are: Cell wall-deficient streptococci Group D nonenterococci In the genera Granulicatella and Abiotrophia Enterococci
In the genera Granulicatella and Abiotrophia
Which single test best separates Klebsiella oxytoca from K. pneumoniae? Citrate Indole Urease Sucrose
Indole
A gram-positive branching filamentous organism recovered from a sputum specimen was found to be positive with a modified acid-fast stain method. What is the most likely presumptive identification? Nocardia spp. Listeria spp. Corynebacterium spp. Bacillus spp.
Nocardia spp.
In this type of antimicrobial susceptibility test, a McFarland 0.5 standardized suspension of bacteria is swabbed over the surface of a Mueller-Hinton agar plate, and paper disks containing single concentrations of each antimicrobial agent are placed onto the inoculated surface. What is the name of this test? Agar dilution Kirby-Bauer Breakpoint MIC
Kirby-Bauer
A leg culture from a nursing home patient grew gram-negative rods on MacConkey agar as pink to dark pink oxidase-negative colonies. Given the following results, which is the most likely organism? TSI = A/A Indole = Neg MR = Neg VP = + Citrate = + H2S = Neg Urease = + Motility = Neg Antibiotic susceptibility: resistant to carbenicillin and ampicillin Proteus vulgaris Enterobacter cloacae Klebsiella pneumoniae Serratia marcescens
Klebsiella pneumoniae
All the following are biochemical features ofSalmonella except: Voges-Proskauer negative Indole negative Lactose positive Hydrogen sulfide positive
Lactose positive
Which of the following tests best differentiates Shigella species from Escherichia coli? Hydrogen sulfide, MR, citrate, and urease Hydrogen sulfide, VP, citrate, and urease Gas, citrate, and VP Lactose, indole, ONPG, and motility
Lactose, indole, ONPG, and motility
A β-hemolytic gram-positive coccus was isolated from the CSF of a 2-day-old infant with signs of meningitis. The isolate grew on sheep blood agar under aerobic conditions and was resistant to bacitracin disc. Which of the following should be performed for the identification of the organism? Latex antigen typing Catalase formation Esculin hydrolysis Oxidase production
Latex antigen typing
What are the names of the two diseases caused by Legionella species? Scalded skin syndrome and Legionnaires disease Malta fever and undulating feve Legionnaires disease and Pontiac fever Rabbit fever and Pontiac fever
Legionnaires disease and Pontiac fever
The goal of the specimen collector when collecting specimens for culture should be to: Make sure the specimen gets to the laboratory Maintain the viability of the living organisms at the site with minimal contamination Get the specimen quickly to get the doctor off the collector's back Avoid hurting the patient when collecting the specimen
Maintain the viability of the living organisms at the site with minimal contamination
All Neisseria are generally all of the following, except? Oxidase positive Aerobic Motile Catalase positive
Motile
Which of the following products is responsible for satellite growth of Haemophilus spp. around colonies of Staphylococcus and Neisseria spp. on sheep blood agar? NAD Oxidase Indole Hemin
NAD
The primary reservoir for staphylococci is: Mouth Ears Throat Nares
Nares
A pure culture of β-hemolytic streptococci recovered from a leg wound ulcer gave the following reactions: CAMP = Neg Hippurate hydrolysis = Neg Bile esculin = Neg 6.5% salt = Neg PYR = Neg Bacitracin = Resistant Optochin = Resistant SXT = Sensitive The most likely identification is: Group A streptococci Nongroup A, nongroup B, nongroup D streptococci Enterococcus faecalis Group B streptococci
Nongroup A, nongroup B, nongroup D streptococci
Chocolate agar is an example of which of the following? Selective media Enriched media Differential media Nonselective media
Nonselective media?
What disease can newborns acquire through a birth canal infected with Neisseria gonorrhoeae? Ophthalamitis Conjunctivitis Blindness Ophthalmia neonatorum
Ophthalamitis
A third-shift technologist is working in microbiology when a cerebrospinal fluid (CSF) specimen comes in. Almost simultaneously, the technician is called to the emergency department to draw blood on seriously injured car crash victims. How should the technologist store the CSF until time permits to work on the CSF specimen? Place the specimen in the refrigerator where it is good for up to 4 hours at 4°C Freeze the specimen Place the specimen in a 35°C incubator for up to 6 hours Pour the specimen into a tube of broth
Place the specimen in a 35°C incubator for up to 6 hours
Lysine Iron Agar (LIA) showing a purple slant and a blackened butt indicates: Citrobacter spp. Salmonella spp. E. coli Proteus spp.
Salmonella spp
The stock cultures needed for quality control testing of deoxyribonuclease (DNase) production are: Serratia marcescens/Escherichia coli Salmonella typhimurium/Escherichia coli Proteus mirabilis/Escherichia coli Escherichia coli/Pseudomonas aeruginosa
Serratia marcescens/Escherichia coli
MacConkey media for screening of hemorrhagic coli 0157:H7 must contain: Sorbitol Urea Citrate Indole
Sorbitol
All of the following staphylococci are coagulase-negative, except: Staphylococcus saprophyticus Staphylococcus aureus Staphylococcus delphini Staphylococcus intermedius
Staphylococcus aureus
Which staphylococcus produces wide zones of beta hemolysis on 5% sheep blood agar? Staphylococcus epidermidis Staphylococcus intermedius Staphylococcus saprophyticus Staphylococcus aureus
Staphylococcus aureus
A woman in her 20s goes to her physician complaining of burning upon urination, frequency, and general malaise. Her physician does a urine culture, and it grows out 25,000 colony-forming units (CFU)/mL of a catalase-positive, coagulase-negative, novobiocin-resistant gram-positive cocci. What is the most likely pathogen? Staphylococcus haemolyticus Staphylococcus saprophyticus Staphylococcus intermedius Staphylococcus epidermidis
Staphylococcus saprophyticus
Which antibiotic inhibits folate synthesis, which provides the essential precursor molecule, pyridine thymidylate, needed in DNA synthesis? Vancomycin Aminoglycosides Sulfamethoxazole Quinolones
Sulfamethoxazole
Differential media: Supports the growth of one type or group of microbes, but not another Supports grouping of microbes based on different characteristics demonstrated in the media Allows the growth of fastidious microbes through the addition of certain growth enhancers Supports the growth most nonfastidious microbes
Supports grouping of microbes based on different characteristics demonstrated in the media
The porphyrin test was devised to detect strains of Haemophilus capable of: Ampicillin degradation Synthesis of hemin Capsule production Chloramphenicol resistance
Synthesis of hemin
What is the cell wall made of in streptococci and enterococci? Teichoic acid and peptidoglycan Lipopolysaccharide and carbohydrates Cholesterol and teichoic acid Protein A and phospholipids
Teichoic acid and peptidoglycan
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: The patient has a line infection The blood cultures are defective There was a low-grade bacteremia The organism is most likely a contaminant
The organism is most likely a contaminant
When performing a Kovac indole test, the substrate must contain: Paradimethylaminobenzaldehyde Indole Ornithine Tryptophan
Tryptophan
How is culture media selected for specimen plating? Determine the supplemental agar needed, as well as broth media Use only broth for the initial inoculation and subculture to plates after 24 hours of incubation The selection of media to inoculate is based on the type of specimen submitted for culture and the organisms likely to be involved in the infectious process Always include nonselective media and differential media to help save a day of reading the culture on the bench
The selection of media to inoculate is based on the type of specimen submitted for culture and the organisms likely to be involved in the infectious process
Which of the following factors would make an organism appear to be more resistant on a disk diffusion susceptibility test? Too many organisms in the inoculum The presence of 0.5% NaCl in the medium A medium with a pH of 7.4 Too little agar in the plate
Too many organisms in the inoculum
An 8-year-old girl was admitted to the hospital with a three-day history of fever, abdominal pain, diarrhea, and vomiting. A stool culture grew many lactose-negative colonies that yielded the following results: Oxidase: Negative TSI: acid/acid Indole: Negative Urease: + Ornithine decarboxylase: + Sucrose: + H2S: Negative Motility at 25°C: + The most probable identification of this organism is: Edwardsiella tarda Providencia stuartii Escherichia coli Yersinia enterocolitica
Yersinia enterocolitica
What bacterium is the causative agent of the plague? Shigella sonnei Citrobacter freundii Salmonella enteritidis Yersinia pestis
Yersinia pestis
Which of the following genes is responsible for oxacillin resistance in Staphylococcus aureus? STAT1 mecA lacZ lacY
mecA
The proper blood-to-broth ratio for blood cultures to reduce antibacterial effect of serum in adults is: 1:2 1:3 1:30 1:10
1:10
How many hours after eating contaminated food do initial symptoms of staphylococcal food poisoning typically occur? 24-48 hours 2-6 hours 12-18 hours 72 hours to a week
24-48 hours
The Voges-Proskauer (VP) test detects which end product of glucose fermentation? Hydrogen sulfide Acetoin Nitrite Acetic acid
Acetoin
A patient with a nosocomial pneumonia has a sputum Gram stain that shows many neutrophils and numerous small gram-negative coccobacilli. The organism grew in 24-hours as mucoid, hemolytic colony on blood agar and a colorless colony on MacConkey agar. The organism had the following characteristics: Oxidase = Neg Catalase = + Nitrate = Neg ONPG = Neg Ornithine decarboxylase = Neg Lysine decarboxylase = Neg The organism is: Acinetobacter baumannii Alcaligenes faecalis Stenotrophomonas maltophilia Moraxella lacunata
Acinetobacter baumannii
All of these stains are commonly used to visualize mycobacteria on a smear except: Acridine orange Ziehl-Neelsen Kinyoun Auramine
Acridine orange
Following a tooth extraction, a patient developed a cervicofacial abscess. What organism, which may be part of the normal anaerobic microbiota of the mouth, is the most likely infecting organism? Bacteroides oralis Peptostreptococcus Diphyllobothrium latum Actinomyces israelii
Actinomyces israelii
Additional methods of definitive identification for the Enterobacteriaceae family include which of the following: Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) All of these options Nucleic acid-based studies Serodiagnosis
All of these options
Antimicrobial susceptibility testing of Bacteroides and Clostridium spp. anaerobes are done by which of the following methods? Agar dilution E-Test Broth microdilution All of these options
All of these options
Variation in colony types seen with fresh isolates of N. gonorrhoeae and sometimes with N. meningitidis are the result of: Pili on the cell surface All of these options Use of a transparent medium Multiple nutritional requirements
All of these options
Which of the following are dimorphic fungi? Sporothrix schenkii Histoplasma capsulatum All of these options Blastomyces dermatitidis
All of these options
Which of the following organisms will display lipase activity on egg yolk agar? Clostridium sporogenes Clostridium novyi All of these options Clostridium botulinum
All of these options
Which class of antibiotics is used for the treatment of serious gram-negative infections as well as infections with Mycobacterium tuberculosis? Cephalosporins Penicillins Tetracyclines Aminoglycosides
Aminoglycosides
An abdominal postoperative wound specimen grew catalase-positive, indole-negative, nonpigmented, nonfluorescent, gram-negative, pleomorphic bacilli (safety pin-shaped) on 20% bile media. The colonies also grew on KVA agar (resistant to kanamycin, vancomycin, and colistin). What is the most likely identification? Prevotella spp. Bacteroides fragilis Fusobacterium nucleatum Porphyromonas spp.
Bacteroides fragilis
Gram-positive cocci in chains are seen of a Gram stain from a blood culture. The organism grows as a β-hemolytic colony. Further tests that could be performed include: Oxidase and deoxyribonuclease Vogues-Proskauer and methyl red Bile esculin, PYR, bacitracin, and hippurate Catalase and coagulase
Bile esculin, PYR, bacitracin, and hippurate
A positive Simmons citrate test is seen as a: Blue color in the medium after 24-hours of incubation at 35°C Yellow color in the medium after 24-hours of incubation at 35°C Green color in the medium after 18-hours of incubation at 35°C Red color in the medium after 18-hours of incubation at 35°C
Blue color in the medium after 24-hours of incubation at 35°C
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 What should be done next? Test the organism with a new lot of antisera Repeat the biochemical tests Boil the organism and retest with the antisera Test with Vi antigen
Boil the organism and retest with the antisera
A 5-year-old nonimmunized male with a persistent cough, fever, and flulike symptoms was admitted to the hospital. Nasopharyngeal swabs were cultured on 15% blood, chocolate, Bordet-Genjou, and Regan-Lowe (with 10% charcoal) agars. All media grew a gram-negative coccobacillus. Carbohydrate and biochemical tests were negative. What is the most likely identification? Haemophilus influenzae Bordetella pertussis Bordetella brochioseptica Haemophilus parainfluenza
Bordetella pertussis
Spirochetes often detected in the hematology laboratory while scanning a blood film, even before the physician suspects the infection, are: Borrelia spp. Leptospira spp. Campylobacter spp. Treponema spp.
Borrelia spp.
Mycobacteria stained by the Ziehl-Neelsen or Kinyoun methods with methylene blue counterstain are seen microscopically as: Bright red rods against a blue background Orange-red rods against a black background Bright blue rods against a pink background . Bright yellow rods against a yellow background
Bright red rods against a blue background
Opportunistic fungi include all of the following, EXCEPT: Coccidioides Aspergillus Rhizopus Fusarium
Coccidioides
Which test is used for the determination of inducible clindamycin resistance in staphylococci and streptococci? D-zone test E-test CAMP test A-test
CAMP test
Which of the following tests aids in the identification of Cryptococcus neoformans? Caffeic acid test Gram-stain Germ tube formation Wood's lamp test
Caffeic acid test
A smear of skin tissue reveals apple-green fluorescent septate hyphae. The smear was most likely prepared using: Calcofluor white Periodic Acid-Schiff Auramine Rhodamine Acridine orange
Calcofluor white
What organism may play a role in Guillain-Barré syndrome (GBS)? Plesiomonas Campylobacter Aeromonas Helicobacter
Campylobacter
The formation of germ tubes presumptively identifies: Candida albicans Candida tropicalis Cryptococcus neoformans Candida glabrata
Candida albicans
A dog bite wound to the thumb of a 20-year-old male patient became infected. Culture grew a gram-negative, slender rod, which was a facultative anaerobe. The following results were noted: Oxidase = + Catalase = + "Gliding" on the agar was noted. Motility = Neg Capnophilic = + What is the most likely identification? Pseudomonas aeruginosa Capnocytophaga canimorsus Acinetobacter spp. Proteus mirabilis
Capnocytophaga canimorsus
Cultures obtained from a dog bite wound produced yellow, tan, and slightly pink colonies on blood and chocolate agar, with a margin of fingerlike projections appearing as a film around the colonies. Given the following results at 24 hours, which is the most likely organism? Oxidase = + Catalase = + Growth on MacConkey agar = Neg Motility = Neg Eikenella spp. Capnocytophaga spp. Aggregatibacter (formerly Actinobacillus) spp. Pseudomonas spp.
Capnocytophaga spp.
Select the medium best suited for the recovery of Y. enterocolitica from a patient with gastroenteritis. Eosin methylene blue agar Blood agar Cefsulodin-irgasan-novobiocin (CIN) agar Hektoen agar
Cefsulodin-irgasan-novobiocin (CIN) agar
The best method to demonstrate ova of Enterobius vermicularis is: Cellophane tape preparation Acid-ether concentration Formalin-ether concentration Zinc sulfate flotation
Cellophane tape preparation
Gram-positive bacilli recovered from two blood cultures from a 60-year-old diabetic patient gave the following results: Spores seen = Neg Hemolysis = + (double zone) Motility = Neg Lecithinase = + Volatile acids by GLC (PYG) = acetic acid and butyric acid What is the most likely identification? Clostridium tetani Clostridium novyi Clostridium sporongenes Clostridium perfringens
Clostridium perfringens
Gram-positive bacilli recovered from two blood cultures from a 60-year-old patient with diabetes gave the following results: Spores seen = Neg Hemolysis = + (double zone) Motility = Neg Lecithinase = + Volatile acids by GLC (PYG) = acetic acid (A) and butyric acid (B) Clostridium novyi Clostridium tetani Clostridium sporogenes Clostridium perfringens
Clostridium perfringens
Egg yolk agar is used to detect which enzyme produced by Clostridium species? Catalase Oxidase Coagulase Lecithinase
Lecithinase
Egg yolk agar is used to detect which enzyme produced by several Clostridium species? Lecithinase β-Lactamase Oxidase Catalase
Lecithinase
Obligate anaerobes, facultative anaerobes, and microaerophiles are terms referring to bacteria that require: Increased nitrogen Decreased CO2 Increased O2 Decreased O2
Decreased O2
The most rapid definitive diagnosis of a genital herpes simplex (HSV-2) infection in a 20-year-old man is made by using which method? Cell culture of vesicle fluid Direct immunofluorescence test for viral antigen in vesicle fluid Detection of anti-herpes simplex in seminal fluid Titer of serum and seminal fluid for antibodies to herpes simplex
Direct immunofluorescence test for viral antigen in vesicle fluid
The adult tapeworm of Echinococcus granulosus is found in the intestine of: Cattle Dogs Humans Sheep
Dogs
When stool examination is negative, the preferred specimen for the diagnosis of suspected paragonimiasis is: Urine Sputum Duodenal aspirate Rectal biopsy
Duodenal aspirate
A pediatric patient who had had been camping with his parents was admitted to the hospital with severe bloody diarrhea and complications of hemolytic uremic syndrome (HUS). Several stool specimens were submitted for culture and the following results noted: Gram staining = Many gram-negative rods, with no WBCs seen Blood agar = Normal flora MacConkey agar = Normal flora MacConkey agar with sorbitol = Many clear colonies (sorbitol negative) Hektoen agar = Normal flora Campy agar = No growth What is the most likely identification? Yersinia spp. Shigella spp. Salmonella spp. E. coli O157:H7
E. coli O157:H7
Which test is the most reliable for the detection of M. pneumonia in serum and for the confirmation of diagnosis? EIA testing and direct antigen testing Cold agglutinin testing using group O RBCs Culture on SP4 glucose broth with arginine Complement fixation
EIA testing and direct antigen testing
All of the following diseases are produced by Treponema except: Elephantiasis Pinta Yaws Syphilis
Elephantiasis
A patient is suspected of having amebic dysentery. Upon microscopic examination of a fresh fecal specimen the following was observed: This indicates infection with: Entamoeba coli Entamoeba histolytica Giardia lamblia Endolimax nana
Entamoeba histolytica
Deoxycholate agar (DCA) is useful for the isolation of: Neisseria spp. Enterobacteriaceae Enterococcus spp. Staphylococcus spp.
Enterobacteriaceae
A 20-year-old female patient presented to the emergency department complaining of abdominal pain, fever, and a burning sensation during urination. An above-normal WBC count, along with pus cells and bacteria in the urine specimen, prompted the physician to order a urine culture. The colony count reported for this patient revealed greater than100,000 col/mL of a nonhemolytic, catalase-negative, gram-positive organism on 5% sheep blood agar. The following test results indicate which organism? PYR = + 6.5% Salt broth = + growth Bacitracin = Neg Bile esculin = + Optochin = Neg Streptococcus pyogenes Streptococcus bovis Enterococcus faecalis Streptococcus agalactiae
Enterococcus faecalis
Charcot-Leyden crystals in stool may be associated with an immune response and are thought to be formed from the breakdown products of: Monocytes Neutrophils Eosinophils Lymphocytes
Eosinophils
A 20-year-old female college student complained of a sore throat and extreme fatigue. The physician noted lymphadenopathy and ordered a battery of tests. Bacterial cultures were negative, as were serological tests for Influenza A and B, HIV-1, Hepatitis B, and antistreptolysin O. Hematology results showed lymphocytosis with atypical lymphocytes. A Monospot test revealed agglutination with horse erythrocytes but no agglutination with guinea pig kidney cells. What is the most likely causative agent of the patient's condition? HIV Herpes simplex virus Epstein-Barr virus Rubella
Epstein-Barr virus
Which technique is used for the confirmation of infection with HIV-1 and HIV-2? ELISA p24 Antigen testing Western blot (immunoblot) assay FDA-approved Nucleic acid test
FDA-approved Nucleic acid test
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? Gelatinase production, growth at 52°C, H2S Growth at 42°C, pyocyanin production, gelatinase production Growth at 37°C, pyocyanin production, OF glucose Pyocyanin production, gelatinase production, OF glucose
Growth at 42°C, pyocyanin production, gelatinase production
Which group of tests best differentiates Enterobacter aerogenes from Edwardsiella tarda? Lysine decarboxylase, urease, and arginine dihydrolase Motility, H2S production, and DNase Motility, citrate, and urease H2S production, sucrose fermentation, indole, and VP
H2S production, sucrose fermentation, indole, and VP
Select the primary and differential media of choice for recovery of most fecal pathogens: MacConkey, blood, birdseed, and Campy agars CNA and Christensen urea agars and thioglycollate media Blood, Campy, Muelle-Hinton agars, and thioglycollate media Hektoen, MacConkey, Campy, and CNA agars
Hektoen, MacConkey, Campy, and CNA agars
A tissue biopsy specimen of the stomach was obtained from a 38-year-old male patient diagnosed with gastric ulcers. The specimen was transported immediately and processed for culture and histology. At 5 days, the culture produced colonies of gram-negative (curved) bacilli on chocolate and Brucella agar with 5% sheep blood. The cultures were held at 35°C to 37°C in a microaerophilic atmosphere. The colonies tested positive for urease. The most likely identification is: Streptococcus bovis Enterococcus faecalis Helicobacter pylori Escherichia coli
Helicobacter pylori
What is the name of the organism that is strongly associated with gastric, peptic, and duodenal ulcers, as well as GI carcinoma? Helicobacter pylori C. curvus H. rectus Campylobacter jejuni
Helicobacter pylori
Strains of Staphylococcus species resistant to the β-lactam antibiotics by standardized disk diffusion and broth microdilution susceptibility methods are called: Heteroresistant Bacteriophage group 52A Cross-resistant Plasmid-altered
Heteroresistant
Which of the following plates should be used to identify H. haemolyticus and H. parahaemolyticus? Brain-heart infusion (BHI) agar with sheep red cells added Chocolate agar and Mueller-Hinton agar with X factor added Horse blood agar and Mueller-Hinton agar with X and V strips Sheep blood agar and chocolate agar
Horse blood agar and Mueller-Hinton agar with X and V strips
Which of the following would be best to differentiate Streptococcus agalactiae from S. pyogenes? A positive bile-esculin reaction Beta-hemolysis on SBA Ability to grow in sodium azide broth Hydrolysis of sodium hippurate
Hydrolysis of sodium hippurate
Humans can serve as both the intermediate and definitive host in infections caused by: Enterobius vermicularis Hymenolepis nana Schistosoma japonicum Ascaris lumbricoides
Hymenolepis nana
Microaerophiles are bacteria that grow: In reduced oxygen concentration but increased carbon dioxide concentrations In low oxygen concentrations In high carbon dioxide concentrations Where little or no oxygen is present
In reduced oxygen concentration but increased carbon dioxide concentrations
What report should be given for the results of the following AFB smear? Number of AFB seen = 2 per 300 fields (1,000× magnification) 2+ 1+ 3+ Indeterminate; repeat with new specimen
Indeterminate; repeat with new specimen
Which single test best separates Klebsiella oxytoca from K. pneumoniae? Indole Urease Citrate Sucrose
Indole
Which of the following drugs are first-line antibiotics used to treat classic tuberculosis for which susceptibility testing is performed by the disk diffusion method on Middlebrook 7H10 or 7H11 agar plates? Ampicillin, penicillin, streptomycin, and carbenicillin Vancomycin, methicillin, and carbenicillin Isoniazid, rifampin, ethambutol, streptomycin and pyrazinamide Ampicillin, penicillin, and methicillin
Isoniazid, rifampin, ethambutol, streptomycin and pyrazinamide
Which of the following is the medium of choice for the selective recovery of gram-negative anaerobes? Phenylethyl alcohol (PEA) agar Cycloserine-cefoxitin-fructose agar (CCFA) Kanamycin-vancomycin (KV) agar THIO broth
Kanamycin-vancomycin (KV) agar
Which of the following is the medium of choice for the selective recovery of gram-negative anaerobes? Phenylethyl alcohol (PEA) agar Cycloserine cefoxitin fructose agar (CCFA) THIO broth Kanamycin-vancomycin-anaerobe (KVA) agar
Kanamycin-vancomycin-anaerobe (KVA) agar
Nonspore-forming, slender, gram-positive, rod-forming palisades and chains were recovered from a vaginal culture and grew well on tomato juice agar. The most likely identification is: Streptococcus spp. Bacillus spp. Neisseria spp. Lactobacillus spp.
Lactobacillus spp.
Which of the following tests best differentiates Shigella species from E. coli? Hydrogen sulfide, MR, citrate, and urease Lactose, indole, ONPG, and motility H2S, VP, citrate, and urease Gas, citrate, and VP
Lactose, indole, ONPG, and motility
A rapidly growing nonseptate mold produced colonies with a gray surface resembling cotton candy that covered the entire plate. Microscopic examination revealed sporangiophores arising between, not opposite, the rhizoids and producing pear-shaped sporangia. What is the most likely identification? Rhizopus spp. Penicillium spp. Aspergillus spp. Lichtheimis (formerly Absidia) spp.
Lichtheimis (formerly Absidia) spp.
What diseases do Borrelia cause? Undulant and hemorrhagic fevers Lyme disease and relapsing fever Rocky Mountain spotted fever and relapsing fever Lyme disease and parrot fever
Lyme disease and relapsing fever
Which test is most useful in differentiating between Citrobacter and Salmonella? Urease production H2S production Indole production Lysine decarboxylase
Lysine decarboxylase
What media are recommended for routine culturing of specimens for the recovery of acid-fast bacilli? Middlebrook 7H10 and cooked meat broth Sabouraud dextrose and LIM broth Löwenstein-Jensen and liquid-based media Thiosulfate-citrate-bile salts-sucrose (TCBS) and thioglycollate broth
Löwenstein-Jensen and liquid-based media
Mycobacteria isolated from the hot water system of a hospital grew at 42°C. Colonies on the Löwenstein-Jensen medium were not pigmented after exposure to light and were negative for niacin accumulation and nitrate reduction. The most likely identification is: Mycobacterium xenopi Mycobacterium marinum Mycobacterium ulcerans Mycobacterium haemophilum
Mycobacterium xenopi
Select the method of choice for recovery of anaerobic bacteria from a deep abscess. Swab of the scalpel used for débridement Needle aspirate after surface decontamination Cotton fiber swab of the abscess area Skin snip of the surface tissue
Needle aspirate after surface decontamination
Colonies growing on MTM and showing a 4+ reaction with the Superoxol test may be considered as a rapid presumptive test for: Neisseria gonorrhoeae Neisseria meningitidis Neisseria lactamica Moraxella (Branhamella) catarrhalis
Neisseria gonorrhoeae
The β-galactosidase test aids in the identification of which Neisseria species? Neisseria lactamica Neisseria meningitidis Neisseria gonorrhoeae Neisseria flavescens
Neisseria lactamica
Infections caused by Y. pestis are rare in the United States. Those cases that do occur are most frequently located in which region? Alaska, Oregon, and Utah Ohio, Michigan, and Indiana New Mexico, Arizona, and California North and South Carolina and Virginia
New Mexico, Arizona, and California
Yeast recovered from the urine of a catheterized patient receiving chemotherapy for cancer gave the following results: CORNMEAL TWEEN 80 AGAR Germ tube = + Pseudohyphae = + Terminal chlamydoconidia = + Blastoconidia = + Arthroconidia= Neg What further testing is necessary? Nitrate reductase and carbohydrate fermentation Carbohydrate assimilation and urease No further testing is needed for identification Urease and niger seed
No further testing is needed for identification
An asymptomatic 25-year-old female patient with persistent nongonococcal urethritis (NGC) and pelvic inflammatory disease (PID) was suspected of being infected with Mycoplasma genitalium. Which category of testing should not be utilized to establish a final identification? Culture PCR Nucleic acid amplification test (NAAT) Real time PCR
Real time PCR
A 65-year-old female outpatient was requested by her physician to submit a 24-hour urine specimen for protein and creatinine tests. He also requested testing for mycobacteria in the urine. Should the microbiology laboratory accept this 24-hour specimen for culture? Yes, if the specimen is for aerobic culture only No, the specimen is unsuitable for the recovery of mycobacteria No, the specimen must be kept at room temperature Yes, if the specimen is kept on ice
No, the specimen is unsuitable for the recovery of mycobacteria
A gram-positive (gram-variable), beaded organism with delicate branching was recovered from the sputum of a 20-year-old patient with leukemia. The specimen produced orange, glabrous, waxy colonies on Middlebrook agar that showed partial acid-fast staining with the modified Kinyoun stain. What is the most likely identification? Streptomyces spp. Rhodococcus spp. Actinomadura spp. Nocardia spp.
Nocardia spp
A gram-positive branching filamentous organism recovered from a sputum specimen was found to be positive with a modified acid-fast stain method. What is the most likely presumptive identification? Corynebacterium spp. Bacillus spp. Nocardia spp. Listeria spp.
Nocardia spp.
Classification of viruses is made by: Complement fixation serology Electron microscopy Nucleic acid composition Cellular inclusion bodies
Nucleic acid composition
Classification of viruses is made by: Nucleic acid composition Electron microscopy Cellular inclusion bodies Complement fixation serology
Nucleic acid composition
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 negative Oxidase negative, glucose positive, and maltose negative Oxidase positive, glucose positive, and maltose positive Oxidase positive, glucose negative, and maltose positive
Oxidase positive, glucose positive, and maltose negative
Presumptive tests used for the identification of Pseudomonas are: Growth on MacConkey, EMB, and XLD agars, and motility Growth on mannitol salt agar and flagellar stain Growth on blood agar and EMB agar, lysine decarboxylation, catalase Oxidase, oxidation-fermentation (OF) glucose (open), OG glucose (sealed), motility, pigment production
Oxidase, oxidation-fermentation (OF) glucose (open), OG glucose (sealed), motility, pigment production
The atmospheric conditions best suited to grow streptococci and enterococci are: High carbon dioxide concentration Oxygen-free atmosphere Room air Low carbon dioxide concentration
Oxygen-free atmosphere
Which of the following is NOT an amoeba? Acanthamoeba Plasmodium spp. Endolimax nana Naegleria fowleri
Plasmodium spp.
Which gram-negative bacilli produce brown to black pigment on KVA agar and brick red fluorescence when exposed to an ultraviolet (UV) light source? Porphyromonas spp. and Prevotella spp. Fusobacterium spp. and Actinomyces spp. All of these options Bacteroides spp. and Fusobacterium spp.
Porphyromonas spp. and Prevotella spp.
Three blood culture specimens taken from a 30-year-old patient with cancer receiving chemotherapy and admitted with a urinary tract infection (UTI) grew lactose-negative, motile, gram-negative rods prior to antibiotic therapy. Given the following biochemical reactions, which is the most likely organism? H2S (TSI) = + Indole = + MR = + VP = Neg Citrate = Neg Urease = + DNase = + (PD) Phenylalanine deaminase = + Gelatin hydrolysis = + Ornithine decarboxylase = Neg Serratia marcescens Klebsiella pneumoniae Proteus mirabilis Proteus vulgaris
Proteus vulgaris
A nonfermenter recovered from an eye wound is oxidase positive, motile with polar monotrichous flagella, and grows at 42°C. Colonies are dry, wrinkled or smooth, buff to light brown, and are difficult to remove from the agar. In which DNA homology group should this organism be placed? Burkholderia pseudomallei Pseudomonas putida Pseudomonas stutzeri Pseudomonas fluorescens
Pseudomonas stutzeri
All of the following are nematodes, except: Wuchereria bancrofti Ascaris lumbricoides Schistosoma mansoni Trichuris trichiura
Schistosoma mansoni
The mycobacteria that produce a deep yellow or orange pigment both in the dark and light are Nonchromogens Rapid growers Scotochromogens Photochromogens
Scotochromogens
What is the primary method used to screen for syphilis infections? Serologic Culture Genome sequencing Microscopy
Serologic
Routine laboratory testing for Treponema pallidum involves: Acid-fast staining Serological analysis Culturing Gram staining
Serological analysis
Which of the following Shigella spp. serotypes is the most often isolated in the United States? Serotype B (Shigella flexneri) Serotype A (Shigella dysenteriae) Serotype C (Shigella boydii) Serotype D (Shigella sonnei)
Serotype D (Shigella sonnei)
A leg-wound culture from a hospitalized 70-year-old man with diabetes grew motile, lactose-negative colonies on MacConkey agar. Given the following biochemical reactions at 24 hours, what is the most probable organism? H2S (TSI) = Neg Indole = Neg MR = Neg VP = + DNase = + Citrate = + Urease = Neg (PD) Phenylalanine deaminase = Neg Ornithine and lysine decarboxylase = + Arginine decarboxylase = Neg Gelatin hydrolysis = + Serratia marcescens Enterobacter cloacae Proteus vulgaris Proteus mirabilis
Serratia marcescens
A culture from an intra-abdominal abscess produced orange-tan colonies on blood agar that gave the following results: Oxidase = + Nitrate reduction = + KIA = Alk/Alk (H2S)+ Motility = + (single polar flagellum) DNase = + Ornithine decarboxylase = + Growth at 42°C = Neg MacConkey agar = NLF (non-lactose fermenter) Pseudomonas aeruginosa Acinetobacter spp. Chryseobacterium spp. Shewanella putrefaciens
Shewanella putrefaciens
For which clinical specimens is the KOH direct mount technique for examination of fungal elements used? Bone marrow CSF Blood Skin
Skin
Which of the following media can be used to culture Campylobacter jejuni? CIN agar Skirrow medium Bismuth sulfite Anaerobic CNA agar
Skirrow medium
Which of the following specimens should be rejected if submitted for anaerobic culture? Sputum Pleural fluid Pus aspirate Blood
Sputum
CNA agar is used primarily for the recovery of: Staphylococcus aureus Neisseria species Pseudomonas aeruginosa Enterobacteriaceae
Staphylococcus aureus
Slime production is associated with which Staphylococcus species? Staphylococcus aureus Staphylococcus epidermidis Staphylococcus intermedius Staphylococcus saprophyticus
Staphylococcus epidermidis
An emergency department physician ordered a culture and sensitivity test on a catheterized urine specimen obtained from a 24-year-old female patient. A colony count was done, and the following results were obtained after 24 hours: Blood agar plate = >100,000 col/mL of gram-positive cocci resembling staphylococci MacConkey agar = No growth CNA plate = Inhibited growth Hemolysis = Neg Novobiocin = Resistant Catalase = + This isolate is: Staphylococcus aureus Micrococcus luteus Staphylococcus saprophyticus Streptococcus pyogenes
Staphylococcus saprophyticus
Furazolidone (Furoxone) susceptibility is a test used to differentiate: Staphylococcus spp. from Pseudomonas spp. Staphylococcus spp. from Micrococcus spp. Streptococcus spp. from Staphylococcus spp. Streptococcus spp. from Micrococcus spp.
Staphylococcus spp. from Micrococcus spp.
A nosocomial infection involving an 80-year-old female patient, recovering from pneumonia, produced many oxidase-negative colonies on MacConkey agar. Further testing results are: Motility = + Maltose = + Resistant to most beta-lactams Glucose = + Resistant to most aminoglycosides The most likely identification is: Stenotrophomonas maltophilia Burkholderia gladioli Pseudomonas aeruginosa Acinetobacter spp.
Stenotrophomonas maltophilia
Culture of the sputum specimen from a 13-year-old patient with CF grew a predominance of short, gram-negative rods that tested oxidase negative. On MacConkey, chocolate, and blood agar plates, the organism appeared to have lavender-green pigmentation. Further testing showed the following: Motility = + Glucose = + (oxidative) Lysine decarboxylase = + DNase = + Maltose = + (oxidative) Esculin hydrolysis = + What is the most likely identification? Pseudomonas aeruginosa Stenotrophomonas maltophilia Burkholderia (P.) cepacia Acinetobacter spp.
Stenotrophomonas maltophilia
Several clinical culture specimens obtained from an immunocompromised patient with prior antibiotic treatment grew aerobic gram-positive cocci. The organism was vancomycin resistant and catalase negative. Additional testing proved negative for enterococci. What other groups of organisms might be responsible? Clostridium spp. and Streptococcus bovis Micrococcus spp. and Gemella spp. Leuconostoc spp. and Pediococcus spp. Streptococcus pyogenes and Streptococcus agalactiae
Streptococcus pyogenes and Streptococcus agalactiae
Which of the following nematodes has a free-living life cycle in soil? Enterobius vermicularis Ancylostoma duodenale Ascaris lumbricoides Strongyloides stercolaris
Strongyloides stercolaris
All of the following are examples of appropriate specimens for the recovery of fungi except: Tissue biopsy Cerebrospinal fluid Aspirate of exudate Swab
Swab
A stool culture from a 30-year-old man suffering from bloody mucoid diarrhea gave the following results on differential enteric media: MacConkey agar = clear colonies XLD agar = clear colonies Hektoen agar = green colonies Salmonella-Shigella agar = small, clear colonies Which tests are most appropriate for identification of this enteric pathogen? TSI, motility, indole, urease, Shigella typing with polyvalent sera TSI, motility, indole, lysine, Salmonella typing with polyvalent sera TSI, indole, MR, and urease TSI, indole, MR, VP, citrate
TSI, motility, indole, urease, Shigella typing with polyvalent sera
Why is a clean-catch midstream urine used for a urine culture as opposed to a clean-catch urine? The first portion of the urine flow washes contaminants from the urethra and the next portion is more representative of the bladder The name was changed, but the procedure remains the same and the entire amount of urine in the bladder is cultures Catheterized specimens are also called clean-catch midstream urine specimen No urine is free from contamination, so just wipe the external genitalia and void into the cup
The first portion of the urine flow washes contaminants from the urethra and the next portion is more representative of the bladder
The breakpoint of an antimicrobial drug refers to: The optimal therapeutic level of drug that is achievable in serum A minimum inhibitory concentration (MIC) of 16 µg/mL or greater An MIC of 64 µg/mL or greater The amount needed to cause bacteriostasis
The optimal therapeutic level of drug that is achievable in serum
Upon review of a sputum Gram stain, the technician notes that the nuclei of all neutrophils present in the smear are staining dark blue. The best explanation for this finding is: The cellular components have stained as expected The sputum smear was prepared too thin The iodine was omitted from the staining procedure The slide was inadequately decolorized with acetone/alcohol
The slide was inadequately decolorized with acetone/alcohol
According to the Kirby-Bauer standard antimicrobial susceptibility testing method, what should be done when interpreting the zone size of a motile, swarming organism, such as a Proteus species? The swarming area should be ignored The results of the disk diffusion method are invalid The swarming area should be measured as the growth boundary The isolate should be retested after diluting to a 0.05 McFarland standard
The swarming area should be ignored
An emergency department physician suspected C. diphtheriae when examining the sore throat of an exchange student from South America. What is the appropriate medium for the culture of the nasopharyngeal swab obtained from the patient? Tinsdale medium Chocolate agar Thayer-Martin agar MacConkey agar
Tinsdale medium
A 60-year-old Brazilian patient with cardiac irregularities and congestive heart failure suddenly dies. Examination of the myocardium revealed numerous amastigotes, an indication that the cause of death was most likely: Leishmaniasis with Leishmania donovani Leishmaniasis with Leishmania braziliense Trypanosomiasis with Trypanosoma gambiense Trypanosomiasis with Trypanosoma cruzi
Trypanosomiasis with Trypanosoma cruzi
Alcaligenes faecalis (formerly A. odorans) is distinguished from Bordetella bronchiseptica with which test? Oxidase Motility Growth on MacConkey agar Urease (rapid)
Urease (rapid)
Kligler iron agar (KIA) differs from triple-sugar iron agar (TSI) in the: Ability to detect H2S production Color reaction denoting production of acid Ratio of lactose to glucose Use of sucrose in the medium
Use of sucrose in the medium
An isolate of S. aureus was cultured from an ulcer obtained from the leg of a 79-year-old female patient with diabetes. The organism showed resistance to methicillin. This isolate should be additionally tested for resistance or susceptibility to: Vancomycin Kanamycin Gentamicin Erythromycin
Vancomycin
S. aureus recovered from a wound culture gave the following antibiotic sensitivity pattern by the standardized Kirby-Bauer method (S = sensitive; R = resistant): Penicillin = R Cephalothin = R Vancomycin = S Ampicillin = S Cefoxitin = R Methicillin = R Which is the drug of choice for treating this infection? Penicillin Vancomycin Cephalothin Ampicillin
Vancomycin
Which of the following is a curved, gram-negative rod that grows on TCBS agar? Vibrio Campylobacter Fusobacterium Clostridium
Vibrio
What is the name of the organism that causes the disease cholera? Vibrio furnissii Vibrio cholerae Vibrio parahaemolyticus Vibrio vulnificus
Vibrio cholerae
Which enteric gram-negative bacillus is best cultured by isolating it in an alkaline peptone water with a pH range of 9.0 to 9.6? Vibrio cholerae Salmonella typhi Shigella sonnei Campylobacter jejuni
Vibrio cholerae
A curved gram-negative rod producing oxidase-positive colonies on blood agar was recovered from a stool culture. Given the following results, what is the most likely identification? Lysine decarboxylase = + Arginine decarboxylase = Neg Indole = + KIA = Alk/Acid VP = Neg Lactose = Neg Urease = ± String test = Neg TCBS = green colonies Vibrio parahaemolyticus Shigella spp. Salmonella spp. Vibrio cholerae
Vibrio parahaemolyticus
How should specimen collection instructions be given to the patient to ensure collection of a good specimen for culture? Verbally and written in English Written, using simple language (in several languages) and pictures to help the patient understand the procedure as it is verbally explained Verbally Verbally, in many different languages
Written, using simple language (in several languages) and pictures to help the patient understand the procedure as it is verbally explained
An immunocompromised 58-year-old female patient on chemotherapy received 2 units of packed RBCs. The patient died 3 days later, and the report from the autopsy revealed that her death resulted from septic shock. The blood bags were submitted for culture, and the following results were noted: GROWTH OF AEROBIC GRAM-NEGATIVE RODS ON BOTH MACCONKEY AND BLOOD AGARS Lactose = Neg Indole = Neg Urease = + Sucrose = + VP = Neg Motility 22°C = + Citrate = Neg H2S = Neg Motility 37°C = Neg What is the most likely identification? Escherichia coli Yersinia enterocolitica Enterobacter cloacae Citrobacter freundii
Yersinia enterocolitica
Cold enrichment of feces (incubation at 4°C) in phosphate-buffered saline prior to subculture onto enteric media enhances the recovery of: Yersinia enterocolitica Enterotoxigenic Escherichia coli Salmonella paratyphi Hafnia alvei
Yersinia enterocolitica
Xylose lysine deoxycholate (XLD) agar is a highly selective medium used for the recovery of which bacteria? Enterobacteriaceae from gastrointestinal specimens Streptococcus spp. from stool cultures Yersinia spp. that do not grow on Hektoen agar Staphylococcus spp. from normal flora
Yersinia spp. that do not grow on Hektoen agar
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 gram-positive cocci in chains and diplococci Moderate gram-negative diplococci Moderate palisading gram-positive bacilli all in moderate amounts a. Pneumococcal pneumonia b. Oropharyngeal flora c. Haemophilus pneumonia d. Anaerobic infection
b. Oropharyngeal flora
Nonselective media supports the: a. Growth of fastidious microbes through the addition of certain enhancers b. Grouping of microbes based on different characteristics demonstrated in the media c. Growth of most nonfastidious microbes d. Growth of one type or group of microbes, but not another
c. Growth of most nonfastidious microbes
All of the following are biochemical characteristics ofVibrio except: reduces nitrate to nitrite ferments glucose oxidase negative halophilic
oxidase negative
All of the following characteristics describe the genus Plesiomonas except: facultative anaerobes oxidase negative motile ferments glucose
oxidase negative
The minimum bactericidal concentration (MBC) test differs from the minimal inhibitory concentration (MIC) test because the MIC test gives the concentration needed at the site of infection to inhibit bacterial multiplications, whereas the MBC gives: the amount of antimicrobial that must be achieved at the infection site to inhibit the organism the amount of antimicrobial that must be achieved at the infection site to kill the organism the highest concentration of antimicrobial that will kill an organism None of these options
the amount of antimicrobial that must be achieved at the infection site to kill the organism
Two serious complications of an infection with group A streptococcal disease are: acute glomerulonephritis and necrotizing fasciitis gangrene and rheumatic fever acute glomerulonephritis and rheumatic fever toxic shock syndrome and scarlet fever
toxic shock syndrome and scarlet fever
Which of the following is not a virulence factor of group A streptococci? M-protein Streptolysin O Protein F Lipopolysaccharide
Lipopolysaccharide
The species of mycobacteria that will give a positive niacin test is Mycobacterium: M. kansasii M. leprae M. fortuitum M. tuberculosis
M. tuberculosis
The microscopic structures that are most useful in the identification of dermatophytes are: Hyaline and spiral hyphae Macroconidia and microconidia Chlamydospores and microconidia Septate and branching hyphae
Macroconidia and microconidia
A neonatal blood culture collected through a catheter grows a small yeast. Microscopically, the yeast appear round at one end, with budlike structure on a broad base at the other end. Growth is enhanced around olive oil-saturated discs. The organism isolated is: Candida lipolytica Candida tropicalis Malassezia furfur Cryptococcus neoformans
Malassezia furfur
Skin scrapings from a young male patient showed many yeast cells of oval and bottle-shapes with monopolar budding. The direct microscopic examination also showed hyphal elements with a "spaghetti and meatball" morphological appearance. The most likely identification of this yeast is? Cryptococcus neoformans Candida albicans Candida glabrata Malassezia furfur
Malassezia furfur
Streptococcus pneumoniae and the viridans streptococci can be differentiated by which test? Bacitracin disk test, 0.04 unit Bile esculin test CAMP test Optochin disk test, 5 µg/mL or less
Optochin disk test, 5 µg/mL or less
Microscopically, Scopulariopsis spp. resemble Penicillium spp. Which of the following best differentiates the two? Growth at 45°C Brush-like conidiophores and large echinulate conidia No hyphae and no phialides Nonseptate hyphae and foot cells
Brush-like conidiophores and large echinulate conidia
At which pH does the methyl red (MR) test become positive? 4.5 6.0 6.5 7.0
4.5
How is Helicobacter pylori presumptively identified? A rapid oxidase test done on gastric scrapings A culture of a gastric biopsy A rapid urease test done on a gastric biopsy A culture of gastric scrapings
A rapid urease test done on a gastric biopsy
Material from a fungus-ball infection produced colonies with a green surface on Sabouraud agar in 5 days at 30°C. Microscopic examination showed club-shaped vesicles with sporulation only from the top half of the vesicle. This hyaline mold is most probably which Aspergillus spp.? Aspergillus niger Aspergillus flavus Aspergillus fumigatus Aspergillus terreus
Aspergillus fumigatus
When collecting specimens that may contain Campylobacter spp. bacteria, what transport medium should they be placed in, if a delay in transport is possible? Amies Buffered glycerol-saline Regan-Lewis Cary-Blair
Cary-Blair
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
The mycelial form of which dimorphic mold produces thick-walled, rectangular, or barrel-shaped alternate arthroconidia? Histoplasma capsulatum Blastomyces dermatitidis Coccidioides immitis Sporothrix schenckii
Coccidioides immitis
Culture of a finger wound specimen from a meat packer produced short gram-positive, non-spore-forming bacilli on a blood agar plate showing no hemolysis. Given the following test results at 48 hours, what is the most likely identification? Catalase = Neg H2S/TSI = + Motility (wet prep) = Neg Motility (gel media 22 oC) = + (bottle-brush growth in stab culture) Bacillus cereus Listeria monocytogenes Erysipelothrix rhusiopathiae Bacillus subtilis
Erysipelothrix rhusiopathiae
The best specimen for recovery of the mycobacteria from a sputum sample is the: 12-hour pooled specimen 24-hour pooled specimen 10-hour evening specimen First morning specimen
First morning specimen
Two blood cultures obtained from a newborn grew β-hemolytic streptococci with the following reactions: CAMP test = + Bile solubility = Neg Bacitracin = Resistant PYR = Neg SXT = Resistant Hippurate hydrolysis = + 6.5% salt = + Bile esculin = Neg Which is the most likely identification? Group A streptococci Group B streptococci Enterococcus faecalis Non-group A, non-group B streptococci
Group B streptococci
A pregnant women was seen by her obstetrician with signs of flulike illness during her second trimester. NAT was ordered for Toxoplasma gondii, rubella, CMV, and HSV-1 and -2. All test results were negative. However, after delivery, the newborn exhibited signs of an infection and failed to survive. Which virus in the mother causes a 90% transplacental infection rate? Hepatitis D Hepatitis A Hepatitis G Hepatitis B
Hepatitis B
Several attendees of a medical conference in the Gulf Coast area became ill after frequenting a seafood restaurant. A presumptive identification of Vibrio cholerae was made after stool specimens from several subjects grew clear colonies on MacConkey agar and yellow colonies on TCBS agar. Which key tests would help eliminate Aeromonas and Plesiomonas from the differential diagnosis? Hemolysis on blood agar and catalase Mannitol fermentation and sodium requirement Oxidase and motility Oxidase and nitrate
Mannitol fermentation and sodium requirement
Several attendees of a medical conference in the Gulf coast area became ill after frequenting a seafood restaurant. A presumptive identification of V. cholerae was made after stool specimens from several subjects grew clear colonies on MacConkey agar and yellow colonies on TCBS agar. Which key tests would help eliminate Aeromonas and Plesiomonas spp.? Oxidase, motility Oxidase, nitrate Mannitol fermentation, Na+ requirement Hemolysis on blood agar, catalase
Mannitol fermentation, Na+ requirement
Which tests are most appropriate to differentiate between Pseudomonas aeruginosa and Pseudomonas putida? Mannitol, nitrate reduction, growth at 42°C Oxidase, motility, pyoverdin Oxidase, motility, lactose Oxidase, ONPG, DNase
Mannitol, nitrate reduction, growth at 42°C
What type of an atmosphere do campylobacters require for growth? Capnophilic and halophilic Anaerobic and moist Microaerophilic and high nitrogen content Microaerophilic and capnophilic
Microaerophilic and capnophilic
A 12-month-old boy who had a fever of 103°F and was listless was taken to the emergency department. He had been diagnosed with an ear infection 3 days earlier. A spinal tap was performed, but only one tube of CSF was obtained from the lumbar puncture. The single tube of CSF should be submitted first to which department? Chemistry Microbiology Hematology Cytology/Histology
Microbiology
Lysostaphin is used to differentiate Staphylococcus from which other gram-positive, catalase-positive organisms? Aerococcus Micrococcus Enterococcus Streptococcus
Micrococcus
Bacitracin resistance (0.04 unit) is used to differentiate: Staphylococcus spp. from Streptococcus spp. Staphylococcus spp. from Neisseria spp. Micrococcus spp. from Staphylococcus spp. Planococcus spp. from Micrococcus spp.
Micrococcus spp. from Staphylococcus spp.
All of the following parasites have mosquitoes as vectors, EXCEPT: Onchocerca volvulus Plasmodium spp. Wuchereria bancrofti Brugia malayi
Onchocerca volvulus
The incorrect match between organism and the appropriate diagnostic procedure is: Schistosoma haematobium—examination of urine sediment Cryptosporidium spp.—modified acid-fast stain Onchocerca volvulus—examination of skin snips Enterobius vermicularis—routine ova and parasite examination
Onchocerca volvulus—examination of skin snips
A sputum specimen from an 89-year-old male patient with suspected bacterial pneumonia grew a predominance of gram-positive cocci displaying α-hemolysis on 5% sheep blood agar. The colonies appeared donut shaped and mucoidy and tested negative for catalase. The most appropriate tests for a final identification are: Optochin, bile solubility, PYR Coagulase, glucose fermentation, lysostaphin Bile esculin, hippurate hydrolysis Penicillin, bacitracin, CAMP
Optochin, bile solubility, PYR
A sputum specimen from an 89-year-old male patient with suspected bacterial pneumonia grew a predominance of gram-positive cocci displaying α-hemolysis on 5% sheep blood agar. The colonies appeared donut shaped and mucoidy and tested negative for catalase. The most appropriate tests for a final identification are: Optochin, bile solubility, PYR Coagulase, glucose fermentation, lysostaphin Penicillin, bacitracin, CAMP Bile esculin, hippurate hydrolysis
Optochin, bile solubility, PYR
Showing resistance to which drug categorizes a strain of S. aureus as MRSA? Oxacillin Colistin Sulfamethoxazole-Trimethoprim Tetracycline
Oxacillin
In addition to motility, which test best differentiates Acinetobacter spp. and Alcaligenes faecalis? Urease Oxidase Flagellar stain Triple sugar iron agar
Oxidase
What biochemical tests will differentiate nonfermenters from Enterobacteriaceae? Citrate Oxidase Voges-Praoskauer Indole
Oxidase
Which of the following tests should be done first to differentiate Aeromonas spp. from the Enterobacteriaceae? Urease OF glucose Oxidase Catalase
Oxidase
What two biochemical tests help distinguishAeromonas from other enterics? Voges-Proskauer (VP) and indole Simmon's citrate and indole Oxidase and indole Oxidase and Simmon's citrate
Oxidase and indole
What Pseudomonas spp. causes pulmonary disease among individuals with cystic fibrosis? P. aeruginosa P. mendocina P. putida P. fluorescencs
P. aeruginosa
Which is the test of choice for the confirmation of Chlamydia trachomatis infection in urine? PCR molecular testing Microimmunofluorescence (MIF) test Enzyme immunoassay antigen testing Culture using McCoy and Hela cells
PCR molecular testing
What organism is likely to cause an infection after a cat bite? Dysgonomonas capnocytophagoides Pasturella spp. Francisella tularensis Campylobacter spp.
Pasturella spp.
Which characteristics/biochemical tests are used to differentiate Burkholderia cepacia from S. maltophilia? Pigment on blood agar, oxidase, DNase Pigment on MacConkey agar, flagellar stain, motility Glucose, maltose, lysine decarboxylase Triple-sugar iron agar, motility, oxidase
Pigment on blood agar, oxidase, DNase
What do aeromonad colonies look like on cefsulodin-irgasan-novobiocin (CIN) agar? Purple colonies Pink colonies Green colonies Clear colonies
Pink colonies
A germ tube-negative, pink yeast isolate was recovered from the respiratory secretions and urine of a patient with AIDS. Given the following results, what is the most likely identification? CORNMEAL TWEEN 80 AGAR Blastoconidia = + Pseudohyphae = Neg Arthroconidia= Neg Urease = + Candida albicans Rhodotorula spp. Trichosporon spp. Cryptococcus spp.
Rhodotorula spp.
When processing throat swabs for a group A Streptococcus culture, the medium of choice is: Human blood agar Horse blood agar Sheep blood agar Rabbit blood agar
Sheep blood agar
A curved gram-negative, rod-producing, oxidase-positive colonies on blood agar was recovered from a stool culture. Given the following results, what is the most likely identification? Lysine decarboxylase = + Arginine decarboxylase = Neg Indole = + KIA = Alk/Acid VP = Neg Lactose = Neg Urease = ± String test = Neg TCBS agar = Green colonies Vibrio cholerae Shigella spp. Salmonella spp. Vibrio parahaemolyticus
Vibrio parahaemolyticus
A halophilic bacterium responsible for gastroenteritis due to consumption of contaminated seafood is: Staphylococcus aureus Salmonella typhimurium Vibrio parahaemolyticus Vibrio cholerae
Vibrio parahaemolyticus
