2016.6.Microbiology
A 49 year old farmer developed a swelling of the neck beneath the left jaw with enlargement of the left posterior cervical lymph nodes. The photomicrograph is representative of a direct gram stain prepared from purulent material aspirated from one of the enlarged lymph nodes. The organism was not acid fast. The most likely identification is:
Actinomyces israelii
Match the clinical conditions with the most probable causative bacterial agent.
Acute urethritis Neisseria gonorrhoeae Scalded skin syndrome Staphylococcus aureus Septic abscesses Streptococcus anginosus Clench fist cellulitis Eikenella corrodens
Which culture agar combinations below will usually be sufficient for MOST routine urine culture investigations?
5% sheep blood and MacConkey
If a blood agar plate and an EMB plate are both inoculated with 0.001 ml of urine, and 90 colonies of Staph aureus grew on the blood agar plate, what should be reported?
90,000 colony forming units/mL of Staphylococci aureus
The fungus illustrated in this photomicrograph was recovered from an induced sputum specimen from a 74 year old man with chronic obstructive pulmonary disease. This isolate is most likely:
A contaminant
Which of the following are useful serological tests to document antecedent Streptococcal infections:
ASO anti-DNAse
Which of the following statements is TRUE with regard to the agents of bioterrorism?
At least a class II biological safety cabinet (BSC)should be used if an aerosol is likely.
This organism is found endemically on the New England seacoast. When seen in peripheral blood smears, it resembles a parasite of the genus Plasmodium. When an organism RESEMBLING malarial parasites is found in the peripheral blood, it is MOST probably:
Babesia
Which of the following organisms display the characteristic "Medusa head" on sheep blood agar (SBA) after 18 hours of incubation at 35°C?
Bacillus anthracis
The BEST clinical specimen for the recovery of Legionella pneumophilia is:
Bronchial washings
A potentially lethal type of food poisoning caused by improperly canned food is caused by:
Clostridium botulinum
A recto-sigmoidoscopy revealed pseudomembranes in a patient with severe diarrhea following prolonged treatment with ampicillin. Which of the following organisms is MOST likely to be isolated?
Clostridium difficile
Which of the following organisms are gram-positive?
Clostridium difficile
Watch the tube effervesce, As I turn the milk into a mess.
Clostridium perfringens
Which one of the following is the INCORRECT match between organism and the appropriate diagnostic procedure?
Echinococcus granulosus - routine ova and parasite examination
C-reactive protein:
Is usually elevated in pediatric bacterial infections
Which one of the following statements about E.coli O157:H7 is false:
It ferments sorbitol rapidly
Which of the following statements concerning C. difficile is NOT true?
It is an aerobic organism.
The disk diffusion method of measuring antimicrobial sensitivity is also termed:
Kirby-Bauer
A 34-year-old female was seen in the dermatology clinic for some lesions on her fingers that had not responded to topical antimicrobial therapy. Tissue was biopsied and sent for histological examination, routine, AFB and fungal cultures. There was no growth on any culture. Acid fast bacilli were seen in the histological preparations. The tissue culture for AFB had been incubated both at 35oC and 32oC, in liquid media and on media with hemoglobin added for several weeks. What is the most likely diagnosis of her skin lesions?
Leprosy
A 30 year old Hispanic pregnant female developed fever and signs and symptoms of meningitis following ingestion of feta cheese sent by relatives in Mexico. The colonies recovered from a positive blood culture is shown in the upper photograph; the microscopic features in the lower photograph. The most likely identification is:
Listeria monocytogenes
An organism isolated from the spinal fluid of a newborn produced small, grayish, slightly translucent beta-hemolytic colonies on sheep blood agar. A Gram stain of the colony showed small gram-positive rods that look like diphtheroids. The organism is MOST likely:
Listeria monocytogenes
A track star was in the locker room after a competition when one of his teammates noticed light brown circular lesions on his upper back. The agent MOST likely responsible for this condition is:
Malassezia furfur
Shown in this photograph is a Kligler Iron agar slant (left) and a Christensen's urea agar slant (right) after inoculation with an unknown bacterial species and incubation for 24 hours at 35oC. The reactions shown permit a presumptive identification of:
Proteus mirabilis
A patient was admitted to the hospital recently with an obvious infection. A sputum specimen was submitted and the microbiologist inoculated it to sheep blood agar. Based on the colony morphology and the alpha hemolysis seen in the image to the right, the most likely identification is:
Streptococcus pneumoniae
Match the illustrations on the right with the corresponding cocci classifications shown below:
Streptococcus pneumoniae A Neisseria species B Streptococci C Staphylococci D
Which of the following does not pose a significant risk of transmitting bloodborne pathogens?
Sweat
The target cell of the AIDS virus is the:
T lymphocyte
Which of the following statements about Rickettsia is false:
They are cultured in many hospital laboratories
Which of the following is a characteristic of Francisella tularensis?
Tiny, weak-staining, gram-negative coccobacilli
Chlamydia trachomatis causes which of the following problems?
Trachoma, a major cause of preventable blindness in the world
Which of the following parasites enters its host through ingestion of infected pork?
Trichinella spiralis
Any laboratory that analyzes microbes or refers specimens that have the potential to contain microbial agents or toxins is a sentinel laboratory.
True
Based on the picture, the chart is correct. Host cells and background material pink | blue - pink Smear thickness 1 cell thick | > 1 cell thick - 1 cell thick Precipitated stain yes | no - no Would this field be appropriate for reading? yes | no - yes
True
If an isolate of E. coli is resistant to 1st and 3rd generation cephalosporins, extended spectrum beta-lactamase (ESBL) activity should be suspected. Therefore, each cephalosporin should be tested individually or another family of antibiotics should be considered.
True
In molecular diagnostic testing, hybridization employs complementary base pair binding of a synthetic strand to DNA or RNA.
True
In this image is a quadrant plate containing brain heart infusion agar supplemented with 6 ug/mL of vancomycin. The right upper quadrant was inoculated with the test strain of Enterococcus faecium. The presence of growth in the inoculated quadrant indicates resistance to vancomycin.
True
Isolates of Escherichia coli, Klebsiella pneumoniae, K. oxytoca and clinically significant isolates of Proteus mirabilis may possess extended-spectrum beta-lactamase (ESBL) activity.
True
Most individuals infected with the 2009 Influenza A H1N1 virus do not require treatment.
True
The age groups that have been most affected by the H1N1 virus are children and younger adults.
True
The recovery of an oxidase-positive, gram-negative diplococcus that tests direct flourescent antibody (DFA) non-reactive should be tested by alternative methods when establishing a fool-proof diagnosis of gonorrhea.
True
The tube coagulase test, shown in this image (upper tube positive), should be performed on all S. aureus-suspicious isolates giving a negative slide coagulase reaction.
True
This microscopic field is representative of other fields that were observed on a Gram-stained smear. Which of the following describes the quality of the smear?
Under-decolorized
A Staphylococcus aureus was recovered from a wound infection and tested for susceptibility using the CLSI guidelines for disk diffusion testing. The following results were detected: Penicillin- R Cefoxitin- R Oxacillin- S Cephalothin- S Vancomycin- S Which drug must be reported as susceptible?
Vancomycin
A small gram-negative rod isolated from an eye grows on chocolate agar but NOT on sheep blood agar. It produces satellite growth around staphylococci on sheep blood agar, however. The organism requires:
X and V factor
Assume you perform microbiology for an institution submitting surveillance cultures for MRSA. Which isolate should receive further workup to rule out methicillin (oxacillin) resistance?
Yellow colonies on Mannitol Salt agar; catalase-positive, coagulase-positive.
The stool specimen from a patient admitted to the hospital with symptoms of appendicitis has a culture with the following characteristics: Gram-negative bacillus Catalase positive Urease positive Weakly fermentative TSI Slant is A/A These reactions suggest that the organism is MOST likely:
Yersinia enterocolitica
Why is Mycobacterium tuberculosis not seen on gram stained smears?
waxy coating on bacterial surface prevents gram stain penetration
Which of the following appear as budding organisms?
yeast
I smear the streak line through And grow best at forty two.
Campylobacter jejuni
Label the parts of this prototypical bacterium:
Cell Wall B Cytoplasmic membrane D Nuclear Material E Flagellum F
The upper image of a blood agar plate illustrates the colonies that were recovered after 36 hours incubation from a wound of the forearm of a 14 year old boy following a dog bite. The colony had a chemical stench odor. The lower image illustrates the gram stain prepared from the colony. The most likely identification is:
Pasteurella multocida
Identify the parasite of a patient with suspected malaria who demonstrates the following findings on a blood smear: - Enlarged RBCs, some with fine brownish granules - > 15 parasites in some cells - Ameboid structures - Schuffner's dots
Plasmodium vivax
The blue color seen in the Simmon's citrate agar slant to the right tube shown in this photograph, indicating a positive reaction, results from:
Production of ammonia from ammonium phosphate
Which of the following tests is helpful in separating Pseudomonas aeruginosa from other members of the Pseudomonas family?
Production of pyocyanin pigment
Match the diagrams of endospores with their corresponding description:
Projecting, Spherical, and terminal A Non-projecting, ovoid, and central B Non-projecting, ovoid, and subterminal C
In the preliminary identification of the Enterobacteriaceae, it is helpful to separate the various species into tribes. Match the names of each of the tribes listed in the left column with the chief biochemical characteristic by which it can be recognized.
Proteeae Phenylalanine deaminase Escherichieae + + - - IMViC reactions Klebselleae Voges Proskauer Edwardsielleae Hydrogen sulfide
A urine sample yielded a lactose negative, Gram-negative bacillus on primary isolation. Biochemical testing showed the following reactions: Oxidase- negative H2S- positive Urea- positive Phenylalanine deaminase- positive The organism which most closely fits this profile belongs to the genus:
Proteus
Bacteria which require oxygen for proper growth are termed:
Obligate aerobes
The images below represent a gram-positive, catalase-negative, non-motile coccus inoculated to bile esculin agar, 6.5% NaCl broth and to 6 µg/mL of vancomycin in Mueller Hinton agar. It should be reported as:
Enterococcus spp., Resistant to vancomycin
Bordet-Gengou potato infusion agar has been the time-honored medium for the recovery of which one of the following organisms?
Bordetella pertussis
Cystine-tellurite blood agar is recommended for the isolation of which organism?
Corynebacterium diphtheriae
The Chinese transcription shown here is most consistent with the cell morphology of:
Corynebacterium diphtheriae
The serum medium and methylene blue stain originally described by Loeffler is helpful in the identification of:
Corynebacterium diphtheriae
Illustrated in this photograph is the surface of a 5% blood agar plate on which has been streaked a lawn of a Corynebacterium species. The zone around the 10ug penicillin disk rules out:
Corynebacterium ureolyticum
Sheep blood agar contains an inhibitor to which of the following organisms:
Haemophilus
The satellite phenomenon on culture plates is MOST often associated with:
Haemophilus inflluenzae
Illustrated in this photograph is the surface of a 5% sheep blood agar plate on which are growing colonies of yellow pigmented Staphylococcus species. Note the tiny semitranslucent colonies that satellite around some of the colonies. Pleomorphic gram-negative bacilli were seen on gram stain. The most likely identification is:
Haemophilus influenzae
Sheep's blood agar is least suitable for the growth of which of the following organisms?
Haemophilus influenzae
What is the primary target of HIV?
Helper T-cell lymphocytes
What two glycoproteins are expressed on the surface of influenza A viruses and are used for subtyping of the viruses?
Hemagglutinin Neuraminidase
I reside inside red blood cells, where I grow and grow until the cells are eventually destroyed.
Plasmodium falciparum gametocytes
When three tubes of cerebrospinal fluid are received in the laboratory they should be distributed to the various laboratory sections as follows:
#1 Chemistry, #2 Microbiology, #3 Hematology
Enterococci can possess both intrinsic and acquired resistance. Which of the following represents the intrinsic resistance of a typical enterococcal strain?
- Aminoglycoside resistance - Resistance to clindamycin and trimethoprim-sulfamethoxasole - Resistance to cephalosporins
What non-bacterial structures are present in this microscopic field of a Gram-stained smear? (Choose ALL that apply)
- Epithelial cells - White blood cells
Match each of the activities listed with the name of the most likely bacterial agent that would cause an associated infection.
- Incurring a deep cat scratch - Pasteurella multocida - Ingestion of unpasteurized milk - Listeria monocytogenes - Stepping on a rusty nail - Clostridium tetani - Skinning small game - Erysipelothrix rhusiopathiae
Clostridium septicum:
- Is an anaerobe - Ferments maltose, lactose, but rarely sucrose - Produces "drum-stick" shaped spores
Which two of the following organisms are gram positive:
- Peptostreptococcus - Streptococcus
The turbidity of the bacterial inoculum of a standard disc diffusion (Kirby-Bauer) susceptibility test is:
0.5 McFarland Standard
The upper photomicrograph illustrates a gram stain of sputum obtained from a 55 year old man with symptoms of bacterial pneumonia. The lower photograph represents the growth of an inoculum from the specimen on 5% sheep blood agar, on which had been placed an optochin ("P") and a 1 ug oxacilin disk. After 18 hours incubation at 37°C in 5% CO2, the zone around the optochin disk is 18mm and around the OX disk is 8mm. The interpretation is that the organism is most likely:
A pneumococcus, penicillin resistant
Which EBV markers would be MOST likely positive for an individual who had infectious mononucleosis 9 years ago?
Anti-VCA (IgG) and anti-EBNA
This suspicious form, shown below at both low (10X) and high dry (40X) power, measures 90 micro meters by 42 micro meters. It was seen in a stool sample.
Ascaris lumbricoides egg
The phenotypic property of Saccharomyces yeast species that is helpful in establishing its species identification is:
Ascospore production
The image on the right of a mold colony on an agar plate is most representative of which of the following molds?
Aspergillus niger
Which of the following is a presumptive test for the identification of Lancefield group A Streptococcus:
Bacitracin susceptibility
What is the MOST common infective agent to be transmitted through blood transfusion that results in morbidity and mortality?
Bacteria
The organism that is a strict anaerobe, non-motile, gram-negative bacillus, occurring in abscesses and associated with peritonitis is MOST likely:
Bacteroides
Which of the following organisms is not an aerobic organism:
Bacteroides
An eleven year old boy developed signs and symptoms of acute appendicitis. At surgery, the appendix was found to be ruptured and encased in a 3 cm in diameter abscess. Aspiration material was inoculated to an anaerobic blood agar plate. Small, gray, nonhemolytic, semiopaque colonies grew anaerobically in 36 hours. The upper photograph illustrates the gram stain features of the organism; the lower photograph is a Presumpto plate indicating the biochemical reactions (reading clockwise from the 12 o'clock quadrant): growth in 20% bile agar, indole negative, esculin hydrolysis positive and lecithinase negative. The bacterial species most likely associated with the abscess is:
Bacteroides fragilis
Cultures from post-abdominal cellulitis grow gram negative pleomorphic rods with the following characteristics: Grows on KV agar but does not show fluorescence Produces black colonies BBE agar Resistant to penicillin Which of the following is the MOST likely identification?
Bacteroides fragilis
A beta-hemolytic streptococcus was isolated from a throat culture. It gave the following biochemical reactions: Bacitracin- Susceptible Bile esculin- Negative 6.5% NaCl- No growth CAMP- Negative SXT- Resistant The presumptive identification would be:
Beta Streptococcus, Group A
Of the molds that are listed, which is considered an obligate pathogen, causing infection in persons who were previously healthy?
Blastomyces dermatitidis
Bordet-Gengou cough plates are used to isolate:
Bordetella pertussis
The federal government has categorized critical biological agents into three groups: A, B, and C. Those agents in category A are highest-priority because they:
Can be easily disseminated or transmitted person-to-person.
A potentially pathogenic yeast that is usually found as normal flora in the oropharyngeal cavity and may produce thrush is called:
Candida albicans
The formation of germ tubes after 2 hours of incubation in plasma at 35°C leads to the presumptive identification of which of the following yeasts?
Candida albicans
The protein component that surrounds the genome is called a:
Capsid
The Gram stain shown in the image was prepared from a positive anaerobic blood culture bottle after 36 hours incubation. Based on the morphology of the bacterial cells (some with spores, noted by the blue arrows), what the most likely identification?
Clostridium septicum
The growth of the colonies shown in the upper image was obtained on blood agar from a sputum specimen after 8 days of incubation at 30°C. The lower image is a photomicrograph of a lactophenol blue mount made from a portion of the colony. The diagnosis is:
Coccidioidomycosis
_______________ is predominantly associated with skin and soft tissue infections (SSTIs), such as abscesses, cellulitis, folliculitis and impetigo.
Community-associated MRSA
Match the names of each of the fungi listed with its appropriate category.
Conidia in clusters Phialophora verrucosa Conidia in chains Alternaria species Conidia in clusters Exophiala species Conidia in chains Cladosporium species
What is the MOST likely identification of an encapsulated yeast in a blood culture bottle from a patient with septicemia with the following additional culture information?: Failure to produce germ tubes Urease positive Produced brown pigment on bird seed agar
Cryptococcus neoformans
The oval or curved multi-celled, dark-staining macroconidia divided by transverse septa only is characteristic of:
Curvularia species
The infective stage for the majority of all intestinal amoebae is the:
Cyst
Which of the following media would you use to isolate Francisella tularensis:
Cysteine-blood agar
The Iodine prep method is used to detect which of the following protozoan stages:
Cysts
Which of the following microscopic techniques is best suited for direct examination of the infectious agent of syphilis?
Darkfield microscopy
What is the purpose of using ethyl alcohol or acetone in the gram stain procedure:
Decolorize all gram negative organisms
The selective medium XLD is seen in this illustration. What is the significance of the black colonies observable on this plate:
Dihydrogen Sulfide production
Which of the following tests would be used to directly document the presence of a specific organism in a clinical specimen:
Direct fluorescent antibody test
Match the names of each of the bacterial species into Bucket A if it most commonly causes disseminated infection or into Bucket B if the associated infection tends to remain localized.
Disseminated infection Vibrio vulnificus Localized infection Staphylococcus aureus Localized infection Erysipelothrix rhusiopathiae Disseminated infection Salmonella typhi
The preliminary identification of bacterial species often is made based on the odor produced by colonies recovered on primary isolation media. Match the names of the bacterial species with its corresponding odor.
Eikenella corrodens Bleach Eugonic Fermenter (EF4) Popcorn Flavobacterium odoratum Peeled apples Pasteurella multocida Mothballs
Which of the following statements about the HBV vaccine is INCORRECT?
Employers may require a fee to administer the vaccine.
This suspicious form, found in a stool sample, measures 15 micro meters.
Entamoeba histolytica
The tube to the left is a slant of esculin medium, the tube to the right contains heart infusion broth with 6.5% sodium chloride. The bacterial species characteristically producing the positive reactions seen in each of these tubes is most likely:
Enterococcus faecalis
Which of the following are common causes of UTI?
Escherichia coli
What is the BEST stock culture for quality control testing of oxidase production?
Escherichia coli/Pseudomonas aeruginosa
One of the key biochemical characteristics by which Escherichia coli serogroup 0157 can be screened from stool specimens is:
Failure to ferment sorbitol
Methicillin resistant Staphylococcus aureus (MRSA) is only a problem for patients who are hospitalized.
False
No additional testing is required when a positive result is obtained using rapid anti-HIV testing technology.
False
The presence of gram-negative intracellular diplococci in a genital specimen from a FEMALE is diagnostic of gonorrhea.
False
There is an effective vaccine available on the market to develop HIV specific immunity.
False
Match the type of hepatitis with its route of transmission
Fecal and Oral Hepatitis A Parenteral Hepatitis B Parenteral Hepatitis C
What is the purpose of the iodine that is used in the Gram stain procedure?
Fixes the crystal violet to the cellular components of gram-positive bacteria
VDRL and RPR are examples of which of the following types of test methodologies?
Flocculation
Which of the following species or organisms is the most likely to be the cause of mycotic keratitis (fungal eye infection)?
Fusarium species
The string test may be helpful in diagnosing an infection with which organism?
Giardia lamblia
The image shows the Gram stain prepared from the positive blood culture. What is the MOST appropriate report?
Gram-positive cocci in chains
Gram-positive cocci in clusters and tetrads were seen on a clinical Gram stain taken from an open wound. Which of the following would be the MOST appropriate preliminary report?
Gram-positive cocci in clusters and tetrads
A Gram stain of the serous exudate is shown in the image. The appropriate report would read:
Gram-positive cocci in tetrads and clusters
Bacterial colonies often emit distinct odors associated with foods. Match the names of each of the foods listed with its associated bacterial species.
Grapes Pseudomonas aeruginosa Popcorn CDC group EF4 Peeled apples Alcaligenes faecalis (odorans) Butterscotch Streptococcus milleri
Within the genus Campylobacter, the laboratory test most helpful in selectively identifying Campylobacter jejuni is:
Hippurate hydrolysis
The transmission of which of the following organisms is associated with the guano of bats?
Histoplasma capsulatum
The colonies shown in the upper image were obtained on blood agar from a sputum specimen after 10 days incubation at 30°C. The lower image is a photomicrograph of a lactophenol blue mount made from a portion of the colony. The diagnosis is most likely:
Histoplasmosis
Which of the following would be considered the definitive host of a parasite:
Host in which parasites reproduce sexually
An occupation or avocation that should be avoided to prevent infection with Francisella tularensis is:
Hunting and skinning small game
How should the organisms that are indicated by the arrows be reported?
Intracellular gram-negative diplococci
Which one of the following combinations of organisms would be appropriate positive and negative controls to verify the specific test functions listed?
Indole - Escherichia coli and Klebsiella pneumonia
This member of the Enterobacteriacea gave these reactions: TSIA . . . . . . . . . . . . . . . . . . A/A, gas (+), no H2S Ornithine . . . . . . . . . . . . . . . Negative Lysine . . . . . . . . . . . . . . . . . Positive Citrate . . . . . . . . . . . . . . . . . Positive Urea . . . . . . . . . . . . . . . . . . Positive Phenylalanine . . . . . . . . . . Negative Motility . . . . . . . . . . . . . . . . Negative This organism is identified as:
Klebsiella pneumoniae
Shown in this photograph are colonies growing on the surface of MacConkey agar. The red pigment, seen both within the colonies and extending into the surrounding agar, is caused by the fermentation of:
Lactose
Buffered charcoal yeast extract agar (BCYE) is the nonselective solid culture medium used for the primary recovery of:
Legionella pneumophila
The Gram stain of a sputum is unremarkable but the culture reveals many small gram-negative rods able to grow only on charcoal yeast extract agar. What is the MOST likely diagnosis?
Legionnaire's disease
Which organ is the primary target of the hepatitis B virus?
Liver
An acid-fast bacillus recovered from a post-surgery wound of a young child had the following characteristics: Rapid growth (3-5 days) on blood and chocolate agar nitrate positive; niacin negative urease positive; catalase 25/68ºC positive; iron uptake positive Which of the following is the MOST likely identification?
M. fortuitum
Which of the following species of Mycobacterium might be associated with contamination of the hot water system in large institutions such as hospitals?
M. xenopi
The bacterial species illustrated in these photographs was recovered from septic peritoneal fluid of a patient undergoing continuous peritoneal dialysis. The most likely identification is:
Micrococcus luteus
Under a Woods' lamp, infected hair strands from several children with tinea capitis showed green fluorescence, and subsequent cultures grew fungi with aerial mycelia and terminal chlamydospores. These isolates are most likely:
Microsporum audouinii
Which of the following best describes the benefits of the RPR or VDRL tests:
Monitoring course of treatment
Surprise. The purulent exudate and the intracellular bacteria (shown by the arrows) as illustrated in this photomicrograph was observed in a direct sputum Gram stain of a 70 year-old patient with chronic obstructive pulmonary disease. The bacterial species that most likely grew out in culture is:
Moraxella catarrhalis
A culture was taken of a conjunctival exudate. The bacterial species, represented by the tiny colonies seen on this chocolate agar plate were recovered after 48 hours incubation at 35°C. The isolate was cytochrome oxidase positive and highly susceptible to penicillin. The most likely identification is:
Moraxella lacunata
Illustrated in these paired photomicrographs are acid fast stains of tissue sections of colon obtained from an AIDS patient with chronic diarrhea, illustrating a heavy infiltration with acid-fast bacilli (upper image), literally engorging the submucous macrophages (lower image). The Mycobacterium species most commonly associated with this infection is:
Mycobacterium avium intracellulare complex
The accumulation of niacin, as shown by the yellow reaction on the test strip shown in the right tube is one of the chief characteristics in the identification of Mycobacterium tuberculosis. Another rarely encountered Mycobacterium species that also accumulates niacin is:
Mycobacterium simiae
Which of the following is the most suitable specimen for the isolation of Bordetella pertussis:
Nasopharyngeal swab
A gram-negative diplococcus is isolated from a throat culture. The isolate grows on Thayer-Martin agar, produces acid from maltose, lactose and glucose and is ONPG positive. The most likely identification of this isolate is:
Neisseria lactamica
An 18 year old student was seen in the college dispensary with sudden onset of headache, fever and stiff neck. A gram stain of a spinal fluid sediment is shown in the photomicrograph. The most probable cause of the acute meningitis is:
Neisseria meningitidis
The bacterial species shown in this composite photograph of a chocolate agar plate and accompanying gram stain, recovered from an autopsy blood culture of a patient dying with Waterhouse Friderichsen syndrome is most likely:
Neisseria meningitidis
Gram-negative cocci that occur in pairs with their adjacent sides flattened, giving them a "coffee bean" appearance (indicated by the arrows in the image), are typical of which of the following bacteria?
Neisseria species
Which one of the following results is typical of Campylobacter fetus subspecies jejuni?
Optimal growth at 42 ºC
Which of the following is not true about members of the Enterobacteriaceae:
Oxidase positive
The bacterial species producing the set of reactions seen in the oxidative/fermentative (OF) dextrose tubes illustrated in this photograph is a (an):
Oxidizer
The increased resistance of MRSA strains to beta-lactam antibiotics is due to production of which of the following penicillin binding proteins (PBPs)?
PBP 2a
This suspicious form was recovered in blood. Please identify the species listed below that matches the parasites shown in the image with arrows.
Plasmodium falciparum
MacConkey agar contains all of the following except :
Penicillin
In this photomicrograph are observed several background dematiaceous hyphae within which is seen a long, flask-shaped, tapered phialide (arrow) that has a flat saucer-like terminus. This feature is most characteristic of:
Phialophora richardsiae
The segmented, dark-staining grains seen in this photomicrograph are most commonly seen in cases of chromomycosis. Which of the fungal species listed below is known to cause this disease?
Phialophora verrucosum
All of the following may cause systemic mycoses EXCEPT:
Piedraia hortai
Host cells (e.g., white blood cells, epithelial cells) will appear what color on a properly stained Gram stain?
Pink
Match the organisms on the right with their appropriate type from the drop down box:
Protozoa Trypansoma, Leischmania Helminths Trichinella, Schistosoma Protozoa Plasmodium Helminths Ascaris, Cestodes
This Gram stain was prepared from a sputum specimen and is viewed under oil immersion (1000X). What is the structure that is indicated by the arrow?
Pseudohyphae/yeast
A gram-negative rod isolated from a burn patient produced a bluish green pigment and the following test results: Characteristic fruity odor TSI: alkaline/alkaline Motility: positive Oxidase: positive Oxidative/Fermentation Glucose: oxidative utilization only The MOST probable genus of this isolate is:
Pseudomonas
A 22 year old construction worker incurred 3rd degree burns to the chest and arms when a boiler he was installing blew up. On the 5th hospital day the weeping wounds became infected, exuding what was described as green pus. The photograph illustrates the gram stain prepared on a direct smear of the exudate. The most likely bacterial cause of the infection is:
Pseudomonas aeruginosa
Exudate from a burn submitted on a swab for bacterial culture grew a gram-negative bacillus that was oxidase-positive, produced an alkaline slant and butt on TSIA, was resistant to numerous antibiotics, and produced a green, water-soluble pigment. This organism would be identified as:
Pseudomonas aeruginosa
The bacterial species, a typical colony of which is illustrated in this photograph, and a common bacterial cause of "swimmer's ear" can be identified as:
Pseudomonas aeruginosa
Which of the following is not necessary for bacteria to grow successfully on artificial media:
Pure isolate
Streptococcus defectivus and Streptococcus adjacens are the names currently given to two species of what were previously called nutritionally variant streptococci. The supplement that must be added to blood culture medium to recover these organisms in cases of "culture negative endocarditis" is:
Pyridoxyl
Some strains of Group F, Streptococcus milleri (anginosus), can carry the group A antigen, potentially leading to a false positive identification of group A, Streptococcus pyogenes. A spot test that is helpful in differentiating these two species and thus preventing a false report is:
Pyrolidonyl-b-napththylamide (PYR)
The core (genome) of the HIV viron contains:
RNA
Match each virus with its appropriate nucleic acid content.
RNA Paramyxovirus RNA Rhabdovirus DNA Poxvirus RNA Orthomyxovirus
HIV is known as a retrovirus because:
RNA is used as the template for DNA synthesis.
The formula for oxidative/fermentative (OF) culture media, for the determination of glucose oxidizers, differs from carbohydrate fermentation media by each of the following properties except:
Relative increase in the salt concentration
This Xylose Lysine Decarboxylase medium shown in this photograph was isolated from a stool specimen on an immunocompetent adult. Your best action would be to:
Report it as no Salmonella or Shigella isolated.
Gram positive cocci isolated from a catheterized urine culture on a 76-year-old male gave the following reactions: Blood agar- creamy, white, opaque colonies Catalase- positive Slide coagulase- negative Tube coagulase- negative Novobiocin- susceptible The next action the MLS should take is:
Report the isolate as coagulase negative staphylococcus
The photomicrograph on the right illustrates single conidia in succession both laterally and around the tip of a straight phialide. This type of sporulation, characteristic of certain species of dematiaceous mold, is called:
Rhinocladiella
Common colds are MOST often associated with which agent?
Rhinovirus
Rocky Mountain spotted fever is transmitted by the bite of a tick infected with:
Rickettsia rickettsii
Which of the following organisms is an obligate intracellular parasite:
Rickettsiae
Which one of the following statements is false?
Rocky mountain spotted fever is almost always geographically restricted to the Rocky mountain region
Which of the following test(s) that are the most useful in separating Listeria monocytogenes from Erysipelothrix rhusiopathiae?
Room temperature motility Catalase Esculin hydrolysis All of the above
Which one of the following does NOT have capsular material as a defense mechanism?
S. aureus
Which of the following streptococcus exhibits a positive bile solubility test:
S. pneumoniae
Illustrated in this photograph are biochemical reactions of an unknown organism. Reading from left to right the tubes are: Kligler Iron Agar (KIA), Sulfide Indole Motility (SIM), Tryptone Broth Indole, Voges Proskauer and Simmons citrate. The reactions are most consistent with a bacterial species belonging to the genus:
Salmonella
Lysine iron agar is a less commonly used culture medium that is most helpful in the identification of:
Salmonella enteritidis
Illustrated in this photograph are the biochemical reactions of an unknown bacterial species produced in Kligler Iron Agar, Sulfide Indole Motility agar, indole broth, Voges Prokauer broth and Simmons citrate. The bacterial species most likely producing the reactions seen here is:
Salmonella typhi
Which one of the following parasites migrates through the circulation (blood) before maturing in the portal venous system?
Schistosoma mansoni
The portion of a tapeworm used for attachment to the host's intestine is called the:
Scolex
The chain of conidia illustrated in this photomicrograph, with the deep-staining truncated bases, are called annelloconidia, and are most characteristic of:
Scopulariopsis brumptii
The Quellung test is useful for which of the following :
Serological typing of Streptococcus pneumoniae
The positive phenylalanine reaction seen in the left tube (green pigmentation in the slant compared to the negative control on the right) may be produced by each of the following bacterial species except:
Serratia marcescens
Which of the following media is a selective medium for Campylobacter jejuni:
Skirrow's blood agar
Match the illustrations with the corresponding classification of bacteria:
Spirilla A Cocci B Vibrios D Bacilli F
Which one of the following general descriptions concerning Brucella species is FALSE?
Spores produced under anaerobic conditions
In a HPV infection, where does the viral DNA replicate?
Squamous epithelial cells
Which of the following organisms will give a positive coagulase test:
Staphylococcus aureus
Which of these organisms is associated with the condition known as toxic shock syndrome?
Staphylococcus aureus
This non-hemolytic Streptococcus was isolated from the blood culture of a patient recently diagnosed with colon cancer. The image below demonstrates 6.5% NaCl broth and bile esculin agar. With further testing, this isolate will most likely be identified as:
Streptococcus bovis
Which one of the following bacteria is the MOST frequent cause of prosthetic heart valve infections occurring after heart surgery?
Staphylococcus epidermidis
This is a catalase-positive, coagulase-negative gram-positive coccus isolated from a urine specimen from a 20-year-old college student. The image below is a Mueller Hinton plate streaked with a 0.5 MacFarland standardized inoculum and a 5 microgram disk of novobiocin after overnight incubation. What is the identification of the isolate?
Staphylococcus saprophyticus
When a urine specimen cannot be cultured immediately it may be:
Stored at 4° C for up to 24 hours
The Optochin (ethylhydrocupreine hydrochloride) disc is MOST often used for the identification of which organism?
Streptococci pneumoniae
Complete hemolysis of sheep blood agar as demonstrated by the image below would be seen in which of the following catalase-negative isolates?
Streptococcus pyogenes
This Gram-positive, catalase negative coccus is shown on sheep blood agar (beta-hemolytic) with a disk of 0.04 U bacitracin and trimethoprim sulfamethoxadole. A beta lysin-producing Staphylococcus aureus is streaked perpendicular to it. What is the presumptive identification of this organism?
Streptococcus pyogenes
Illustrated in this photomicrograph of a lactophenol blue preparation of a urine sediment is a cluster of yeast cells that were presumptively identified as Cryptococcus species. Further characteristics that may assist in confirming this identification are:
Strong urease activity Strong phenoloxidase activity
If a bacteria produces the enzyme tryptophanase to break down the amino acid tryptophan, which of the following tests will be positive with Kovac's reagent?
indole test
What is the most helpful feature in differentiating the Zygomycetes from the other hyaline molds in the clinical mycology laboratory?
The production of spores within sporangia
Which of the following statements is true regarding the Gram-stained smear that is represented by this image?
The smear is underdecolorized, and shows precipitated stain.
The most likely primary site of infection represented by the Staphylococcus species growing on the surface of this agar plate with a 2mm zone of inhibition around a 5ug novobiocin disk is:
The urinary tract
Illustrated in this photograph is a 5% sheep blood agar plate on which are growing colonies of an unknown bacterial species recovered from a wound culture. All of the following direct tests would be helpful in making an immediate presumptive identification except:
Thermostable endonuclease
Which of the following organisms are gram negative:
Vibrio
Illustrated in this photograph is the surface of a thiosulfate citrate bile sucrose (TCBS) agar plate on which are growing colonies of an unknown bacterial species from a diarrheal stool specimen. The most likely identification is:
Vibrio cholerae
A cerebrospinal (CSF) cell count is 1000 cells/µL. The cells on differential are predominantly lymphocytes. CSF protein is moderately elevated and the glucose is normal. No microorganisms were observed on a Gram's stain smear of the CSF sediment. This condition is MOST likely:
Viral meningitis
India Ink is used to:
Visualize capsule
Which of the following assays is routinely used for confirmation of HIV infections:
Western blot
This photograph is of an isolate from a stool culture on a 4-year-old child with gastroenteritis. The medium contains cefsulodin, irgusan, novobiocin, bile salts, mannitol, neutral red, and crystal violet. Further identification tests will most likely identify this isolate as:
Yersinia enterocolytica
Penicillin G, ampicillin, carbenicillin, and methicillin are antimicrobial agents whose MAIN biological function is to:
inhibit cell wall synthesis
Mycobacterium tuberculosis can be spread from person to person via which transmission method?
airborne
The size of the zone of suppressed growth on a sensitivity plate using sensitivity disks is referred to as the zone of:
inhibition
The susceptibility of a bacterium to each drug on a sensitivity plate using antibiotic disks is demonstrated by the diameter of the zone of:
inhibition
In order to speciate a swarming Proteus organism found on an eosin methylene blue agar plate, the BEST approach would be to:
determine Indole production, phenylalanine and urease activity
The Gram stain report to be issued based on the microscopic characteristics seen in the image on the right would most correctly be, "many WBC with..." (Choose the BEST response)
gram positive cocci in pairs.
One of the BIGGEST problems with isolating Francisella is that these organisms:
grow so slowly
Dematiaceous molds can be broadly separated into two major groups; the agents of chromomycosis and clinically insignificant commensals or contaminants. The agents of chromomycosis grow: more slowly than; more rapidly than; or generally at the same rate as the clinically insignificant commensals or contaminants?
more slowly than
Which virus is the MOST common etiological agent of viral respiratory diseases in infants and children?
respiratory syncytial virus
An acid-fast bacillus is isolated and produces an orange pigment when grown in either the light or the dark. Which type of organism has most likely been isolated?
scotochromogen
The ONPG (ortho-nitrophenyl-Beta-D-galactopyranoside) test should be used to determine what?
separation late lactose fermenters from lactose negative bacteria
The TPI, VDRL, RPR, and Kahn tests are used to provide presumptive identification of which infection?
syphilis, Treponema pallidum
Match each hyaline mold from the drop-down list to its corresponding colony and microscopic description. The mold colonies are illustrated in the image on the right.
- Microsporum canis - Upper left image Multi-celled, rough walled macroconidia with a tapered terminal cell - Aspergillus niger - Upper right image Dense aggregates of echinulate, brown-black conidia - Acremonium species - Lower left image Loose clusters of elliptical conidia arranged in a "diphtheroid" pattern - Scopulariopsis species - Lower right image Chains of large, lemon-shaped annelloconidia
The colonies shown in the blood (BAP) agar (upper) and MacConkey (MAC) agar (lower) biplate are a 24 hour growth from an aerobic blood culture bottle that became positive at 12 hours after inoculation. The appearance of the colonies on MAC agar rules out the following two bacterial species:
- Pseudomonas aeruginosa - Streptococcus pneumoniae
Which statements about melt curve analysis are TRUE? (Choose all that apply.)
- The melting temperature of double stranded DNA depends on its base composition and length. - All PCR products for a specific primer pair should have the same melting temperature. - At the melting point, the probe separates from the target strand and fluorescence rapidly decreases.
Which of the following scenarios represents appropriate detection of MRSA by the Kirby Bauer method?
MHA; direct colony suspension; 35oC; cefoxitin disk; 24 hour incubation
