Microbiology

The entire smooth, convex Mycobacterium species colonies growing on 7H10 agar were observed to be dark yellow pigmented early in culture even before having been exposed to light. This isolate was found to be Tween-80 positive as seen in the reaction tubes in the bottom photograph. Select from the multiple choices the presumptive identification of this isolate. Select one: a. Mycobacterium gordonae b. Mycobacterium fortuitum c. Mycobacterium kansasii d. Mycobacterium marinum,

a. Mycobacterium gordonae

Surprise! Animals are not the only creatures with bacteria. The bacterial species causing onion rot is: Select one: a. Shewanella putrifaciens b. Burkholderia cepacia c. Pantoea agglomerans (Erwinia herbicola) d. Klebsiella planticola

b. Burkholderia cepacia

The colonies shown in this photograph were grown on Guizotia abyssinica (bird seed) agar at 30˚ C for 72 hours. The most likely identification is: Select one: a. Cryptococcus laurentii b. Cryptococcus neoformans c. Candida parapsilosis d. Saccharomyces cerevisiae

b. Cryptococcus neoformans

Stenotrophomonas maltophilia and Burkholderia cepacia share each of the following EXCEPT for which characteristic? Select one: a. Decarboxylation of lysine b. Cytochrome oxidase activity c. Production of colonies with a yellow pigment d. Good growth on MacConkey agar

b. Cytochrome oxidase activity

What is the primary target of the Hepatitis B virus? Select one: a. Heart b. Liver c. Lungs d. Blood cells

b. Liver

What is the primary target of HIV? Select one: a. Heart b. Liver c. Lungs d. T-helper cells

d. T-helper cells

In a HPV infection where does the viral DNA replicate? Select one: a. Squamous epithelial cells b. Glandular cells c. Intraepithelial cells d. White blood cells,

a. Squamous epithelial cells

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: Select one: a. Streptococcus pneumonia b. viridans streptococcus c. Streptococcus pyogenes d. Streptococcus agalactiae,

a. Streptococcus pneumonia

Chlamydia trachomatis causes which of the following problems? Select one: a. Trachoma a major cause of preventable blindness in the world b. Zoonosis in birds and the cause of parrot fever in humans c. A skin disease found predominantly in tropical areas,

a. Trachoma, a major cause of preventable blindness in the world

The lecithin hydrolysis indicated by the tips of the arrows in this photograph of an egg yolk agar plate, may be produced by each of the following Bacillus species except: Select one: a. Bacillus cereus b. Bacillus subtilis c. Bacillus mycoides d. Bacillus anthracis

b. Bacillus subtilis

Illustrated in this photograph are two Middlebrook 7H-11 plates incubated at 35 degrees C on which are growing colonies of an unknown Mycobacterium species. The plate on the left was incubated in the dark the plate at the right had been exposed to light for 24 hours. The most likely identification is: Select one: a. Mycobacterium gordonae b. Mycobacterium kansasii c. Mycobacterium tuberculosis d. Mycobacterium marinum

b. Mycobacterium kansasii

The condition most likely to predispose a person to septicemia by viridans streptococci is: Select one: a. Hypertrophy of the prostate gland b. Poor oral hygiene c. Chronic obstructive pulmonary disease d. Indwelling catheter

b. Poor oral hygiene

Which of these laboratory methods are recommended for confirmation of influenza A H1N1 subtype infection? Select one: a. Immunofluorescence assay (IFA) b. Reverse transcriptase-polymerase chain reaction (RT-PCR) c. Rapid influenza A/B test

b. Reverse transcriptase-polymerase chain reaction (RT-PCR)

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? Select one: a. photochromogen b. scotochromogen c. BCG d. Mycobacterium tuberculosis e. Non-pathogenic

b. Scotochromogen

The appearance of the bacterial colonies growing on the surface of the Hektoen Enteric agar plate shown in this photograph are consistent with each of the following bacterial species except: Select one: a. Serratia marcesens b. Shigella sonnei c. Klebsiella oxytoca d. Enterobacter sakasakii

b. Shigella sonnei

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: Select one: a. Moraxella catarrhalis b. Neisseria gonorrhoeae c. Neisseria meningitidis d. Acinetobacter baumannii,

c. Neisseria meningitidis

Illustrated in the photomicrograph is the tail portion of an adult worm of a filarial nematode as it may be observed in a peripheral blood smear. These worms measure up to 300 um in length and commonly inhabit the lymphatics. This nematode species more commonly inhabit the lymphatics. This nematode species more commonly involves the lymphatics of the inguinal region resulting in swelling below the knee in what is known as "elephantiasis". The species indicated in this exercise can be presumptively determined by the orientation of the nuclei within the tail section (arrows). From the nematode species listed below indicate the most likely species identification. Select one: a. Brugia malayi b. Wuchereria bancrofti c. Loa loa d. Dirofilaria immitis

, a. Brugia malayi

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: Select one: a. The cause of chronic bronchitis b. The cause of invasive pulmonary disease c. The cause of allergic bronchopulmonary disease d. A contaminant

D. A contaminant

Any laboratory that analyzes microbes or refers specimens that have the potential to contain microbial agents or toxins is a sentinel laboratory. Select one: True False

True

In molecular diagnostic testing hybridization employs complementary base pair binding of a synthetic strand to DNA or RNA. Select one: True False

True

The media used to isolate Legionella pneumophilia should contain which of the following additives? Select one: a. X and V factors b. Hemin and vitamin K c. Charcoal and yeast extract d. Dextrose and laked blood e. Lactose and vitamin E

c. Charcoal and yeast extract

In observing the slow-growing 7-day-old dark brown colonies growing on Sabouraud Dextrose with Grain Heart Infusion (SABHI) agar, note the black pigment is that extends to the reverse of the colony. This provides for a presumptive indication of one of the fungi involved in chromoblastomycosis. The species identification of this fungus can be made by observing the distinctive fruiting heads illustrated in the bottom image. From the list of choices below, select the identification of the fungal species presented. Select one: a. Fonsecaea pedrosoi b. Exophiala jeanselmei c. Phialophora verrucosa d. Cladophialophora carrionii,

c. Phialophora verrucosa

The colonies growing on Middlebrook agar shown in the upper left photograph were recovered after 5 days incubation from an aspirate of a superficial skin infection. Gram stain revealed branching bacilli as seen in the lower image. These were non-acid fast. Illustrated in the upper right photograph are colonies growing on casein medium demonstrating hydrolysis. The presumptive identification is: Select one: a. Nocardia asteroides b. Nocardia brasiliensis c. Streptomyces species d. Oerskovia turbata

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Match the viruses below with their associated diseases 1.Hepadnavirus 2. Arbovirus 3. Parvovirus 4. Paramyxovirus

1. Hepatitis 2. Enchapalitis 3. Fifth Disease 4. Measles-Mumps

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: Select one: a. Micrococcus luteus b. Staphylococcus aureus c. Staphylococcus cohnii d. Stomatococcus mucilagenosus

a. Micrococcus luteus

The dematiaceous colony illustrated here grew to a diameter of 3-4 cm in 5 days. The dematiaceous fungus that can be ruled out is: Select one: a. Phialophora verrucosum b. Exserohilum species c. Alternaria species d. Ulocladium species

a. Phialophora verrucosum

Cultures from past-abdominal cellulitis grow gram negative pleomorphic rods with the following characteristics: Grows on KV agar but does not show fluorescence Produced black colonies BBE agar Resistant to penicillin Which of the following is the MOST likely identification? Select one: a. Bacteroides fragilis b. Fusobacterium nucleatum c. Bacteroirds Prevotella d. Veillonella sp e. Bacteroides distasonis

a. Bacteroides fragilis

The long pencil-shaped, multi-celled, thin, and smooth-walled macroconidia illustrated in this image are characteristic of which species? Select one: a. Exserohilum species b. Bipolaris species c. Drechslera species

a. Ecerohilum species

Which one of the following organisms is sensitive to bacitracin: Select one: a. Group A Streptococcus b. Group B Streptococcus c. Group D Streptococcus d. Staphylococci

a. Group A Streptococcus

Illustrated in this photograph is a sulfide indole motility (SIM) tube (left) and an esculin hydrolysis slant (right) after inoculation with an unknown gram positive bacillus and incubation at 30 degrees C for 24 hours. Based on the reactions observed the most likely identification is: Select one: a. Listeria monocytogenes b. Erysipelothrix rhusiopathiae c. Kurthia species d. Lactobacillus species

a. Listeria monocytogenes

Which of the following species of Mycobacterium might be associated with contamination of the hot water system in large institutions such as hospitals? Select one: a. M. xenopi b. M. ulcerans c. M. marinum d. M. haemophilum e. M. tuberculosis

a. M. xenopi

The observation of darkly pigmented colonies on blood agar as illustrated in this photograph is somewhat of a surprise. The colonies of each of the following bacterial species may have an appearance similar to that seen here except: Select one: a. Prevotella melaninogenica b. Stentotrophomonas maltophilia c. Chromobacterium violaceum d. Pseudomonas aeruginosa

b. Stentotrophomonas maltophilia

Observe the Optochin "P" disc reaction illustrated in the upper left photograph on the surface of blood agar. Heavy growth of tiny alpha hemolytic colonies are observed growing on the agar surface that extend to the outer margins of the paper disc. The gram stain presented in the lower photomicrograph reveals small gram-positive cocci lying singly, in small clusters, and more typically in long chains. This isolate has been recovered from blood cultures in cases of post-valvular endocarditis. From the list of multiple choices, select the presumptive identification of this isolate. Select one: a. Streptococcus pneumoniae b. Streptococcus agalactiiae c. Streptococcus viridans d. Streptococcus anginosus,

c. Streptococcus viridans

The entire smooth, golden yellow-pigmented non-hemolytic colonies on the surface of the blood agar plate seen in the upper image have been recovered in hospital acquired infections from patients with cystic fibrosis. A Gram stain prepared from one of the colonies as shown in the lower image, reveal long, narrow gram-negative bacilli arranged singly. Polar flagella would be seen in flagellar stains. All carbohydrate reactions are negative except for the oxidative utilization of maltose. Positive biochemical reactions for DNA'se and for esculin assist in making a definitive identification. Based on these observations, select from the multiple choices the identification of this isolate. Select one: a. Burkholderia cepacia b. Stenotrophomonas maltophilia c. Flavobacterium meningosepticum d. Bordetella bronchiseptica,

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In the upper bi-plate image are shown colonies growing on MacConkey and on blood agar (right). Relatively large confluent gray white colonies are observed growing on blood agar, while smaller smooth convex colonies with a deep red pigmentation are growing on MacConkey agar. Note that the pigmentation is confined to the colonies growing on MacConkey agar that does not diffuse into the adjacent agar. In follow up to making a presumptive identification, observe that the colonies growing on the DNA'se agar in the lower image show a positive reaction with clearing of the adjacent agar, compared to the growth of a negative control growing in the streak lines to the left. From these observations, select from the multiple choices the presumptive identification of this isolate. Select one: a. Proteus vulgaris b. Serratia marcescens c. Providencia stuartii d. Citrobacter koseri,

b. Serratia marcescens

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: Select one: a. Candida albicans b. Epidermophyton floccosum c. Microsporum audouinii d. Microsporum gypseum e. Trichophyton rubrum,

c. Microsporum audouinii

The photomicrograph shows a close-in view of erythrocytes three of which are infiltrated by what appear to be ring like malarial trophozoites. More mature ones are arranged as doublets. The smear was obtained from a 40-year-old forester working in Connecticut who was complaining of malaise and fatigue. The infected erythrocytes are not enlarged and are normo-chromic. From these observations select from the multiple choices the presumptive identification of the etiologic agent. Select one: a. Plasmodium falciparum b. Plasmodium vivax c. Babesia microti d. Borrelia burgdorferi

c. Babesia microti

Illustrated in the top image are small entire gray-white colonies growing on the surface of an anaerobic blood agar plate. Hemolysis is absent. Small, gram negative coccobacilli with rounded ends are seen on gram stain. Positive biochemical reactions include strong hydrolysis of esculin, positive indole and the fermentation of glucose and other carbohydrates (saccharolytic). From these observations, select the correct identification of this isolate from the choices below: Select one: a. Veillonella parvula b. Prevotella melaninogenica c. Bacteroides fragilis d. Fusobacterium nucleatum,

c. Bacteroides fragilis

This photomicrograph was prepared from tease mounts of 3 day-old smooth white yeast colonies obtained from an aspirate of nasal fluid of a middle aged patient with sinusitis. Note the clusters of small blastoconidia along the pseudohyphae and also the larger spherical chlamydospores (arrow), as observed in the right lower corner. From the multiple choices, select the identification of this yeast isolate. Select one: a. Candida glabrata b. Candida tropocalis c. Candida albicans d. Candida parapsilosis

c. Candida albicans

Which of the following fungal infections is endemic in the southwestern US desert regions? Select one: a. Histoplasmosis b. Blastomycosis c. Coccidioidomycosis d. Sporotrichosis

c. Coccidioidomycosis

Among the gram-positive bacilli the unique species producing H2S as seen in the Kligler Iron Agar slant illustrated in this photograph is: Select one: a. Listeria monocytogenes b. Corynebacterium striatum c. Erysipelothrix rhusiopathiae d. Bacillus circulans

c. Erysipelothrix Rhusiopathiae

The tubes below are the Hugh and Liefson O/F basal medium with glucose and a pH indicator of bromthymol blue. The image below demonstrates a reaction of: Select one: a. Glucose-fermenter b. Glucose-oxidizer c. Glucose non-oxidizer d. Sucrose-fermenter

c. Glucose non-oxidizer

Illustrated in the top mage are colonies after 12 days of incubation of a Mycobacterium specied that developed a yellow pigmentation upon exposure to light (photochromagen). A positive niacin accumulation reaction is shown in the lower image suggestive of M. tuberculosis a species that can be ruled out because of the colony pigment production. From the multiple choices, select the name of this photochromogenic Mycobacterium species. Select one: a. Mycobacterium gordonae b. Mycobacterium scrofulaceum c. Mycobacterium simiae d. Mycobacterium chelonae,

c. Mycobacterium simiae

Illustrated in the top image are 10 day old rough buff, gray-white colonies growing on Middlebrook 7H11 agar. These colonies are commonly recovered from expectorated or induced sputum specimens obtained from patients with signs and symptoms of pneumonia. The appearance of these colonies provide for a presumptive identification, supported by the positive yellow-pigmented niacin reaction seen in the reagent tube in the lower photograph. From these observations, select from the multiple choices the presumptive identification of this isolate. Select one: a. Mycobacterium fortuitum b. Mycobacterium kansaii c. Mycobacterium tuberculosis d. Mycobacterium gordonae,

c. Mycobacterium tuberculosis

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: Select one or more: a. Pseudomonas aeruginosa b. Klebsiella pneumoniae c. Streptococcus pneumoniae d. Escherichia coli

c. Streptococcus pneumoniae and a. Pseudomonas aeruginosa

Illustrated in this photograph is an H & E-stained section of a gastric biopsy obtained from a patient with suspected peptic ulcer disease. Based on the biopsy findings the bacterial species that would be most likely to be recovered is: Select one: a. Salmonella typhi b. Campylobacter hyointestinalis c. Yersinia paratuberculosis d. Helicobacter pylori,

d. Helicobacter pylori

In order to speciate a swarming Proteus organism found on an eosin methylene blue agar plate the BEST approach would be to: Select one: a. inoculate to a 4% agar plate and subculture to McConkey's b. determine motility and lysine decarboxylase activity c. determine Indole production, phenylalanine and urease activity d. determine utilization of sodium acetate and citrate e. inoculate a tube of thioglycolate broth

c. determine Indole production, phenylalanine and urease activity

Which one of the following viruses requires a complex lymphoblastoid cell culture and is rarely if ever diagnosed by culture: Select one: a. Varicella-Zoster Virus b. Herpes Simplex Virus c. Cytomegalovirus d. Epstein-Barr Virus,

d. Epstein-Barr Virus

The image illustrates a Gram stain of a vaginal smear obtained from an 11-year-old girl suspected of being a victim of sexual abuse. The appearance of intracellular gram-negative diplococci (GNDC) as seen in the segmented neutrophil at the tip of the arrow, can represent different organisms. Therefore, recovery of th eacterial species in culture and biochemical identifications is needed before the case can be resolved. Each of the following may appear as intracellular GNDC EXCEPT for which organism? Select one: a. Neisseria gonorrhoeae b. Moraxella osloensis c. Acinetobacter baumannii d. Gardnerella vaginalis,

d. Gardnerella vaginalis

Observation of each of the following characteristics is helpful in differentiating between Nocardia species and Mycobacterium species except: Select one: a. Partial acid fast staining b. Filamentous rods that branch c. Musty basement smell of the colonies d. Gram positive staining

d. Gram positive staining

Illustrated in the top photograph is a 4-day growth of a dematiaceous colony characteristic of one of the phaeohyphomyces but is not species specific. In the lactophenol blue stained microphotograph is a dark staining conidiophore from which along both sides are produced multiple long tapered multicellular conidia are attached. From these observations, select from the multiple choices the identification of this fungus. Select one: a. Ulocladium species b. Nigrospora species c. Exserohilum species d. Helminthosporium species,

d. Helminthosporium species

The combination of organisms that is correctly paired with the reactions for appropriate quality control (one organism positive for the reaction and one organism negative for the reaction) are: Select one: a. Coagulase: Staphylococcus saprophyticus and Staphylococcus epidermidis b. H2S production: Proteus mirabilis and Salmonella c. Phenylalanine deamination: Escherichia coli and Yersinia enterocolytica d. Indole: Escherichia coli and Proteus mirabilis

d. Indole: Escherichia coli and Proteus mirabilis

The colonies shown in this 5% sheep blood agar (left) and MacConkey agar (right) split frame photograph are most likely those of: Select one: a. Escherichia coli b. Enterobacter sakasakii c. Proteus mirabilis d. Morganella morganii

d. Morganella morganii

The reactions observed in this Kligler Iron Agar slant (left) and Christensen's urease slant (right) provide the presumptive identification of: Select one: a. Citrobacter freundii b. Edwardsiella tarda c. Salmonella typhimurium d. Proteus mirabilis

d. Proteus mirabilis

Compared to blood agar media chocolate blood agar FAVORS the growth of which organisms? Select one: a. anaerobic bacteria b. facultative anaerobes c. all gram-positive bacteria d. more fastidious bacteria e. hemolytic bacteria,

d. more fastidious bacteria

Select form the following choices the specimen that is inadequate for the recovery of anaerobes and should be summarily rejected upon receipt in the microbiology laboratory. Select one: a. Swab specimens taken from a deep sub-cutaneous abcess b. Needle aspirate in an anaerobic E-swab tube c. Syringe aspirate hand-carried to microbiology laboratory d. Uterine cervical swab in Cary-Blair transport medium

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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 MycobacteriumI species most commonly associated with this infection is: Select one: a. Mycobacterium gordonae b. Mycobacterium tuberculosis c. Mycobacterium bovis d. Mycobacterium avium intracellulare complex

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Illustrated in the photograph is what appears to be a tapeworm strobili in which the individual proglottids appear broader than long. If this segment was observed in a stool specimen select from the multiple choices the presumptive identification. Select one: a. Diphyllobothrium latum b. Taenia saginata c. Hymenolepis nana d. Vegetable artifact,

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Which of the following diagnoses can be excluded based on laboratory data and current symptoms and history? Select one: a. HDV b. Acute hepatitis C c. Acute hepatitis A d. Chronic hepatitis B e. All of the above

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Sodium thiosulfate is often added to selective culture media to: Select one: a. Inhibit the grow of gram positive bacteria b. Detect hydrogen sulfide c. Provide sulfur atoms for H2S positive isolates d. Serve as a pH buffer

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