Purple & Gold Book Micro Sample Questions

A "rice water stool" is characteristic of patients infected with ____________.

Vibrio cholerae

A sample of material from bluish purulent head lesions is submitted for analysis. A gram negative, motile, non-spore-forming, oxidase positive rod was isolated. This organism is most likely____________.

Pseudomonas aeruginosa

A gram stained smear from a genital soft chancre demonstrated small gram negative rods arranged in tangled chains. You would suspect the cause of the chancroid to be

Haemophilus ducreyi

Organisms of this genus are gram negative, motile rods. A few are chromogenic and produce a red non-water soluble pigment. Some have been implicated in septicemia, pulmonary and urinary tract infections. One member of this genus is

Serratia marcescens

Which characteristic is most useful in differentiating Citrobacter and Salmonella?

Lysine decarboxylase

A gram stain from a sputum specimen demonstrates many gram positive cocci in chains and pairs. Numerous small alpha streptococci are observed on the primary blood agar plate. To determine if these organisms are Streptococcus pneumoniae which of the following tests should be performed?

Optochin susceptibility

Loeffler's medium is used as a primary isolation medium for

Corynebacterium diptheriae

Autoclave sterilization of lab media requires which of the following pressure, temperature and time parameters?

15 lbs pressure, 121C for 15min

Clinical diagnosis of rabies in infected animals is dependent upon brain tissue observation of:

Negri bodies

Which of the following results is typical of Campylobacter jejuni?

Optimal growth at 42C

The use of penicillin/aminoglycoside to treat endocarditis due to Streptococci Group D represents a

synergistic relationship

Characteristics indicating an appropriate sputum collection would be microscopic finding of?

A clean catch urine specimen from a female with a suspected UTI showed a gram positive cocci that were catalase positive, coagulase negative, and Staph latex negative. On the Microscan panel, growth in the novobiocin well was noted. The most likely organism is

Staphylococcus saprophyticus

The treatment of choice for methicillin resistant Staphylococcus is

Vancomycin

The most likely cause of subacute bacterial endocarditis is

Streptococcus viridans

The organism known for its stormy fermentation and double zone of beta hemolysis under anaerobic conditions causes

Gas gangrene

The bacteremic Waterhouse-Friderichsen syndrome is associated with

Neisseria meningitidis

The specimen of choice in a case of epiglottitis is collected from the:

blood

A specimen from a female complaining of vaginitis emitted a "fishy" odor when mixed with 10% KOH. A wet prep showed some white cells and epithelial cells covered with small gram variable rods. The most likely organism is

Gardnerella vaginalis

A photochromogenic mycobacterium isolated at 30C is most likely

M. marinum

A scotochromagenic mycobacterium showing hydrolysis of Tween 80 in 7 days is probably

M. gordonae

A gram negative rod, isolated from the urine of a female with recurrent UTI, was oxidase negative, urease positive, showing A/A with H2S on TSI and red/black on LIA is most likely

Proteus mirabilis

An organism recovered from a diarrheal stool was K/A with no gas or H2S on TSI, lysine negative, oxidase negative, urease negative, and citrate negative. The most likely organism is

Shigella sonnei

A cause of acute infectious infantile diarrhea is

Rotovirus

Specimens for viral culture should be transported in

nutrient medium with antibiotics

A fungal specimen isolated from the bone marrow of a patient with a pulmonary infection showed tuberculate macroconidia at 30C and yeast-like cells at 36C. Identify the most likely dimorphic fungi with these characteritics

Histoplasma capsulatum

A yeast like organism was isolated from a sputum specimen. On cornmeal agar, this yeast produced mycelia with thick walled terminal chlamydoconidia. this organism is most likely

Candida albicans

Thick-walled yeast cells bearing single buds attached by a broad base are observed in an aspirated clinical specimen. The organism is most likely:

Blastomyces dermatitidis

Crust from a cauliflower-like lesion on the hand exhibited brown spherical bodies 6-12 mm in diameter when examined microscopically. After 3 weeks of incubation at room temperature, a slow-growing black mold grew on Sabouraud dextrose agar. Microscopic examination revealed Cladosporium, Phialophora and Fonsecaea types of sporulation. The probable identification of this organism is:

Fonsecaea pedrosoi

In order to prove a yeast is dimorphic, which of the following tests is performed?

Incubate yeast subculture at 37C

Which of the following organisms causes visceral larval migrans

Toxocara canis

Enterobius vermicularis infection is usually diagnosed by finding eggs from

cellulose tape preps

The infective stage for Strongyloides stercoralis is the

falciform larve

If humans ingest the egg of Taenia solium, they may develop

Cystercercosis

A silver methenamine stained slide of a bronchial washing from an AIDS patient is examined. Which of the following organisms is most likely to be identified?

Pneumocystis jiroveci

A blood smear showed crescent shaped gametocytes in several red cells. What is the most probable identity

Plasmodium falciparum

Which organism is transmitted to humans by ticks and blood transfusions?

Babesia

Which of the following can cause a fatal meningoencephalitis?

Naegleria fowleri

The trophozoite of which organism is characterized by "falling leaf motility" two nuclei, an axostyle, 4 pair of flagella and a sucker on the underside of the organism?

Giardia lamblia

The ameba which can cause liver or lung abscesses is

Entamoeba histolytica

Which of the following eggs may not be detected in zinc flotation procedures

Schistosoma mansoni

Which trophozoite is suspected if ingested red cells are seen on a saline wet prep?

Entamoeba histolytica

Pregnant women are to avoid cleaning litter boxes of their house cats until after delivery to prevent congenital infection of

Toxoplasma gondii

A patient visiting from overseas is hospitalized due to suspected tuberculosis. The sputum sample submitted to the laboratory is bloody with orange brown flecks. Preliminary TB tests are negative. which of the following parasites may be suspected?

Paragonimus wetermani

Which of the following cysts has a nucleus with a prominent karyosome, a clear halo, no achromatic granules, no peripheral chromatin?

Endolimax nana

Differential diagnosis of Cryptosporidium parvum and Cyclospora cayetanensis is based on:

Oocyst size --Cyclospora is larger