CCMLS - Micro Content #2

Select the statement that is correct concerning the influenza viruses. a. pandemics are characteristically produced by influenza A b. they are DNA viruses c. the virus is transmitted by insect vectors d. the incidence of infection peaks in the summer months

a. pandemics are characteristically produced by influenza A

A cyst 70 microns in length (shown below), whose double wall enclosed a ciliated organism, would be: a. transmitted by a mosquito to man b. acquired by accident by man since it customarily infects swine c. a member of the Sporozoa d. demonstrated only by trichrome stain

b. acquired by accident by man since it customarily infects swine

Which virus has been implicated in adult gastroenteritis resulting from ingestion of contaminated food (especially shellfish) and water? a. norwalk-like virus b. rotavirus c. hepatitis C virus d. coronavirus

a. norwalk-like virus

The laboratory receives a urine specimen from a knowledgeable infectious disease department requesting that Fletcher and/or Stuart medium be inoculated and incubated at 30 C. One of the diagnoses being considered must be: a. leptospirosis b. tularemia c. rickettsiosis d. erysipeloid

a. leptospirosis

Observation of hyaline or dematiacious hyphae is an early clue in the identification of common airborne fungi. Which of the following genera contains species which is a dematiacious contaminant? a. Alternaria sp. b. Penicillium sp. c. Paecilomyces sp. d. Fusarium sp.

a. Alternaria sp.

A fungal colony grows rapidly on Sabouraud Dextrose Agar as a white colony type with a dense production of aerial, blue-green spores. On lactophenol cotton blue preparations, swollen conidiophores bear sterigmata and conidia in chains. The most likely identification of this isolate is: a. Aspergillus sp. b. Helminthosporium sp. c. Penicillium sp. d. Scopulariopsis sp.

a. Aspergillus sp.

Alternately dark light staining barrel-shaped arthrospores are characteristic of one genus of fungi. Name this genus and species. a. Coccidioides immitis b. Sporothrix schenkii c. Candida albicans d. Aspergillus fumigatus

a. Coccidioides immitis Coccidioides immitis is a monomorphic fungi which grows only as a yeast phase in the body (it grows as spherule which are usually seen in the lung. Each spherule has multiple endospores inside). The mold form of Coccidiodes shows alternating light dark arthrosphores making up the hyphal elements. Coccidioides is a rapidly growing organism which fills the SAB plate in 3-5 days (sometimes called a lid lifter). It is white and fluffy and very contagious. It should only be handled in a biological hood.

This saprobe has been associated with corneal ulcers, ulcerated skin and mycetomas. It is a rapid grower, usually producing a lavender pigment and on microscopic exam crescent-shaped, septate macroconidia are seen. It is most likely: a. Fusarium b. Penicillium c. Curvularia d. Sepedonium

a. Fusarium

A fungus is believed to multiply in various cells of the reticuloendothelial system and be involved in a pulmonary infection which resembles tuberculosis. This is a dimorphic fungus which on Sabouraud Dextrose agar produced conidia bearing hyphae that are round with small projections and appears yeast-like on blood agar. Which of the following could this dimorphic fungus be? a. Histoplasma capsulatum b. Coccidioides immitis c. Blastomyces dermatitides d. Cryptococcus neoformans

a. Histoplasma capsulatum The dimorphic fungus that produces tuberculate macroconidia at 25 C on SAB agar and grows as a yeast form in cells of the RES system is Histoplasma capsulatum. The organism will grow on BHI agar at 35-37 C in an incubator in the yeast form.

A specimen has been standing in the laboratory overnight. Upon examination the next day you find motile larvae which have a long buccal cavity. No ova are found. Identification of this organism is: a. Hookworm, rhabditiform larvae b. Strongyloides stercoralis, rhabditiform larvae c. Strongyloides stercoralis, adult worm d. Hookworm, filariform larvae

a. Hookworm, rhabditiform larvae

What organism is the cause of Kala-Azar? a. Leishmania donovani b. Leishmania brazilensis c. Trypanosoma cruzi d. Trypanosoma gambiense

a. Leishmania donovani

An acid-fast bacillus (AFB) has been isolated from the sputum of a patient suspected of having a mycobacterial pulmonary disease. The organism is a slow-growing isolate that produces cream-to-tan colored colonies when grown in the dark in the incubator and after exposure to light. This organism is most likely which of the following mycobacteria? a. Mycobacterium avium-intracellulare complex b. Mycobacterium chelonei c. Mycobacterium kansasii d. Mycobacterium scrofulaceum

a. Mycobacterium avium-intracellulare complex

Which malarial organism has a banana-shaped gametocyte that can be easily differentiated from that of the other species? a. Plasmodium falciparum b. Plasmodium ovale c. Plasmodium malariae d. Plasmodium vivax

a. Plasmodium falciparum

The malarial organism whose schizont resembles a pie, in which the merozoites form a rosette around malarial pigment is: a. Plasmodium malariae b. Plasmodium vivax c. Plasmodium ovale d. Plasmodium falciparum

a. Plasmodium malariae

Which malarial organism characteristically has a band form trophozoite stretching across the red cell? a. Plasmodium malariae b. Plasmodium ovale c. Plasmodium vivax d. Plasmodium falciparum

a. Plasmodium malariae

Which malarial organism, shown below, infects red cells which then become fimbrinated? a. Plasmodium ovale b. Plasmodium malariae c. Plasmodium falciparum d. Plasmodium vivax

a. Plasmodium ovale

Microfilariae of this tissue roundworm are sheathed. Nuclei do not extend into the posterior tip. What is this parasite? a. Wuchereria bancrofti b. Brugia malayi c. Loa loa d. Mansonella ozzardi

a. Wuchereria bancrofti

The clinical expression "acute respiratory disease" (ARD) is most frequently used to designate: a. an adenovirus infection b. a herpres-simplex infection c. a poxvirus infection d. a cytomegalovirus infection

a. an adenovirus infection

The purpose of Staib Agar (also known as Niger seed or Bird Seed agar) is to: a. assist with the identification of Cryptococcus neoformans which produces a brown to maroon pigment in 1 week at 25 C b. assist with the identification of Trichophyton rubrum which produces a red pigment in 3 days at 25 C c. stimulate sporulation of macroconidia of Trychophyton mentagrophytes d. differentiate Microsporum audouinii from Microsporum canis

a. assist with the identification of Cryptococcus neoformans which produces a brown to maroon pigment in 1 week at 25 C

The following Western blot results are regarded as a positive for HIV-1: a. bands pg41 and/or p24 b. bands ts9 and p 24 c. bands pg88 and/or p24 d. bands pg41 and pg88

a. bands pg41 and/or p24

Which of the following viruses is implicated along with Epstein-Barr virus as a cause of infectious mononucleosis? a. cytomegalovirus b. coxsackie A virus c. coxsackie B virus d. hepatitis B virus

a. cytomegalovirus

The most rapid definitive diagnosis of a genital herpes simplex (HSV-2) infection in a 20 year old male is made by which of the methods below? a. direct immunofluorescence test for viral antigen in vesicle fluid b. titer of serum and seminal fluid for antibodies to herpes simplex c. detection of anti-herpes simplex in seminal fluid d. cell culture of vesicle fluid

a. direct immunofluorescence test for viral antigen in vesicle fluid

Which of the following is NOT characteristic of Dientamoeba fragilis? a. easily recognized by its jerky motility b. no known cyst stage, trophozoite shaped like an amoeba c. one or two nuclei which have no peripheral chromatin d. flagellate which is an intestinal pathogen

a. easily recognized by its jerky motility

The type of cell culture that best supports the growth of human cytomegalovirus (CMV) is: a. human fibroblast cells b. HeLa cells c. hep-2 cells d. primary monkey kidney cells (PMK)

a. human fibroblast cells

The most common causes of viral pneumonia in adults are: a. influenza and adenovirus b. hepatitis A and B viruses c. coxsackie A and B viruses d. herpes simplex and cytomegalovirus

a. influenza and adenovirus

A 7 year old male presents with tinea capitis. Direct examination of hair for fluorescence under a Wood's lamp is positive with a bright yellow-green fluorescence. The infection is thought to be caused by either Microsporum canis or Microsporum audouinii. Suspicions of M. canis can be confirmed by: a. the ability of the organism to grow and sporulate on polished rice grains b. demonstration of endothrix invasion of the hair c. salmon-colored reverse of colony and abundant microaleuriospores (microconidia) on Sabouraud's Dextrose agar d. positive hair baiting technique

a. the ability of the organism to grow and sporulate on polished rice grains Both species caus extothrix hair infections. Microsporum audoinii will grow prolifically on polished rice whereas Microsporum canis grows poorly if at all. In this test sterile polished rice and distilled water are places in a sterile screw-capped bottle. The fungus is inoculated without agar onto the polished rice. The bottle is incubated 8-10 days. M. canis produces large multi-celled rough thick walled spindle shaped macroconidia with pointed ends. The macroconidia are connected to the conidiophore by a breakaway cell. M. audouinii does not produce many macroconidia and they are often distorted. The hair baiting technique is only used to confirm an ID that is inconclusive.

A colony taken from a ring-like lesion on the trunk of a 56 year-old male grows out a colony with abundant tear-drop shaped microconidia. If Trichophyton mentagrophytes and Trichophyton rubrum are the suspected infectious agents, how might the two be differentiated? a. urease test, hair-baiting technique, and production of red pigment on 1% glucose cornmeal agar b. urease test, hair-baiting technique, and endothrix versus ectothrix infection c. hair-baiting technique, production of pigment on 1% glucose cornmeal agar, and growth on polished rice d. urease test, hair-baiting technique, and growth on polished rice

a. urease test, hair-baiting technique, and production of red pigment on 1% glucose cornmeal agar Organism Hair baiting Urease reverse red pigment T. rubrum Neg Neg Pos T. mentagrophytes Pos Pos Neg

Which of the following specimens would be best to isolate cytomegalovirus? a. urine and throat swab b. urine and feces c. feces and CSF d. throat swab and CSF

a. urine and throat swab

Which technique is most widely used for the confirmation of infection with human immunodeficiency virus (HIV-1)? a. western blot (immunoblot) assay b. enzyme-linked immunosorbent assay (ELISA) c. complement fixation d. nucleic acid testing (NAT)

a. western blot (immunoblot) assay

An adult worm whose posterior is fatter than its anterior and whose egg is bile stained, oval, with bipolar plugs is: a. whipworm - Trichuris trichiura b. pinworm - Enterobius vermicularis c. hookworm - Ancylostoma duodenale d. roundworm - Ascaris lumbricoides

a. whipworm - Trichuris trichiura

It is usually quite difficult to impossible to identify a fungal culture before it is mature. However, the presence of hyaline septate hyphae and a young conidiophore with a foot cell and a swollen vesicle are excellent clues. What organism is this? a. Acremonium sp. b. Aspergillus sp. c. Paecilomyces sp. d. Scopulariopsis sp.

b. Aspergillus sp.

In an iodine preparation of feces, an amebic cyst appears to have a basket nucleus and a large glycogen mass that stains reddish-brown. The most probable identity of the cyst is: a. Entamoeba histolytica b. Iodamoeba butcshlii c. Naegleria fowleri d. Entamoeba hartmanni

b. Iodamoeba butcshlii

The acidophilic inclusion bodies that are pathognomonic of rabies are: a. Koplick bodies b. Negri bodies c. "owl-eye" bodies d. Donovan bodies

b. Negri bodies

Chromoblastomycosis is worldwide in distribution. Typically itchy cauliflower-like ulcerations occur on the arms or legs of workers exposed to contaminated soil or splinters. Pus smears taken from issue show brown-black yeast-like cells that occur in tetrads. Dark pigment is also observed in the mycelial colonies grown on Sabouraud Dextrose Agar. Hyphael elements are described as brown and septate with vase shaped conidiophores which support clusters of oval conidia. The causative agent is most likely a member of which genus? a Cladosporium sp. b. Phialophora sp. c. Candida sp. d. Allescheria boydii

b. Phialophora sp. This dematiaceous fungi causes Chromoblastomycosis.

Which malarial organism prefers to invade older red cells? a. Plasmodium ovale b. Plasmodium malariae c. Plasmodium falciparium d. Plasmodium vivax

b. Plasmodium malariae

Which of the following species of fungus is usually encapsulated, urease positive and typically produces mucoid, red colonies? a. Cryptococcus neoformans b. Rhodotorula rubra c. Saccharomyces cerevisiae d. Trichophyton rubrum

b. Rhodotorula rubra Rhodotorula sp. or Rhodotorula rubra is the only orange to red yeast that is clinically significant.

From the list of descriptive elements given, select the species whose major characteristics are described incorrectly: a. Blastomyces dermatitides, thick walled yeast cells with broad-based buds at 37 C b. Sporothrix schenckii, thick walled yeast cells with multiple buds at 25 C c. Coccidioides immitis, spherule with multiple small endospores in a sputum specimen d. Histoplasma capsulatum, spherical tuberculated macroconidia at 25 C

b. Sporothrix schenckii, thick walled yeast cells with multiple buds at 25 C S. schenkii has delicate hyphae at 25 C that have flowerettes on the end of a delicate conidiophore or oval shaped tear-drop condia in a sleeve-like arrangement.

This nematode is acquired from eating undercooked pork when the larvae encysts in skeletal muscle. Diagnosis is made from the typical encysted larvae found in muscle biopsy. What is the genus and species of this organism? a. Trichuris trichiura b. Trichinella spiralis c. Ancylostoma duedonale d. Ascaris lumbricoides

b. Trichinella spiralis

A 15 year old male was treated for favus. The colony that grew on a SAB culture revealed light brown macroscopic growth. No micro or macro conidia were observed. The distinguishing characteristic on microscopic examination was favic chandeliers or "moose antlers". The etiologic agent of this infection is most likely: a. Trichophyton violaceum b. Trichophyton schoenleinii c. Microsporum audouinii d. Epidermophyton floccosum

b. Trichophyton schoenleinii Trichophyton schoenleinii causes favus, a severe form of ringworm of the scalp that leads to scaring and baldness. The isolate only rarely forms microconidia. The key macroscopic element is favic chandeliers (moose antler formations of the hyphal elements) and chlamydoscopes. Macroconidia are usually not seen.

Maduromycosis is a chronic and commonly deforming disease frequently caused by Pseudallescheria boydii. Diagnosis may be made on the basis of clinical observation and by identifying the causative agent in KOH mounts of pus from lesions. If Pseudallescheria boydii is the infecting agent, the pus will contain: a. brown granules b. brightly colored yellow, sometimes white, granules c. no granules d. black granules

b. brightly colored yellow, sometimes white, granules Pseudoallescheria boydii (the sexual stage of the fungus) produces bright yellow, sometimes white, granules in the tissue phase. These can be seen in drainage from the site. They are eumycotic granules in which hyphael elements with parallel sides (representing mycelium) can be seen. The asexual (mold stage) is called Scedosporium apiospermum.

Hepatitis A is most frequently spread by: a. injection of blood or serum form an infected person b. fecal-oral contamination c. sexual contact d. infection with contaminated needles

b. fecal-oral contamination

Chickenpox, "shingles," infectious mononucleosis, genital herpes, and fever blisters are all caused by: a. poxviruses b. herpetoviruses c. adenoviruses d. picornaviruses

b. herpetoviruses

Which of the DNA viruses is the causative agent of Molluscum contagiosum? a. herpesviruses b. poxviruses c. papovaviruses d. adenoviruses

b. poxviruses

The adults of Ancylostoma duodenale may be distinguished from those of Necator americanus by the following: a. length of buccal cavity b. presence or absence of teeth c. number of uterine branches d. number of nuclei

b. presence or absence of teeth

Which virus belonging to the Reoviridae group causes gastroenteritis in infants and young children but asymptomatic infection in adults? a. coxsackie B virus b. rotavirus c. respiratory syncytial virus d. rhabdovirus

b. rotavirus

The tease mount technique is a rapid method for preparing fungal colonies for microscopic examination. The major drawback is: a. lactophenol cotton blue stain does not kill the mycelia b. structural continuity between spore, hyphae and fruiting structures is not always preserved c. uptake of lactophenol cotton blue by hyphal elements makes hyaline elements appear dematiacious d. small fungal colonies cannot be identified

b. structural continuity between spore, hyphae and fruiting structures is not always preserved

This aseptate mold has a predilection for invading blood vessels and is known to be fatal in 7 days. A 13 year old diabetic had this organism cultured from the sinus cavities as a broad hyphal element without septations. Upon culturing, the organism was found to have internodal rhizoids. What is the causative organism? a. Rhizopus b. Mucor c. Absidia d. Exophilia

c. Absidia The Zygomycetes invade blood vessels and are aseptate. Absidia has internodal rhizoids.

An 85 year old female was admitted to the hospital with abdominal cramps and diarrhea of approximately one week's duration. She appeared cachectic and severely dehydrated and gave a history of eating poorly for several months prior to the onset of the above symptoms. The direct smear of a fecal specimen revealed an oval trophozoite measuring approximately 90 U and containing a funnel shaped depression and a kidney shaped nucleus. Other inclusions were not visible. This organism was identified as: a. Entamoeba coli b. Giardia lamblia c. Balantidium coli d. Isospora belli

c. Balantidium coli

A bulldozer operator became ill while working on a new highway in the San Joaquin Valley. He developed chest pain, anorexia, headache and general malaise, and myalgia with fever. Chest x-ray showed pneumonic infiltrate and a single, well-defined nodule in the left lower lobe. His WBC and sedimentation rate were slightly elevated. Although no fungus was seen in the direct examination of a sputum specimen, processing included a culture on Sabouraud's Dextrose Agar with chloramphenicol and cycloheximide. Within 3 days at 28 C this culture produced moist grayish growth, and a white aerial mycelium began to develop. If this fungus was the cause of infection, it was most likely: a. Aspergillus fumigatus b. Blastomyces dermatitides c. Coccidioides immitis d. Cryptococcus neoformans

c. Coccidioides immitis This is the mold phase of Coccidioides immitis which is a rapid grower at room temperature. Coccidioides immitis is a monomorphic fungi which grows only as a yeast phase in the body (it grows as spherule which are usually seen in the lung. Each spherule has multiple endospores inside). The mold form of Coccidiodes shows alternating light dark arthrosphores making up the hyphal elements. Coccidioides is a rapidly growing organism which fills the SAB plate in 3-5 days (sometimes called a lid lifter). It is white and fluffy and very contagious. It should only be handled in a biological hood.

Knowledge of its nocturnal periodicity is especially important in the diagnosis of infection with which of the following tissue round worms? a. Dracunculus medinensis b. Loa loa c. Onchocerca volvulus d. Wuchereria bancrofti

d. Wuchereria bancrofti

A mucoid appearing yeast-like organism was isolated from sputum. No hyphae were produced on Cornmeal agar. The organism is nitrate negative, positive for inositol assimilation and urease positive at 37 C. These findings are typical of: a. Candida krusei b. Cryptococcus terreus c. Cryptococcus neoformans d. Trichosporum beigelii

c. Cryptococcus neoformans Cryptococcus neoformans is a mucoid yeast that causes CSF and lung infections, epecially in the immunocompromised such as HIV + patients. On biochemical testing, the isolate is urease + and assimilates inositol but not many other sugars. It also grows as a maroon-brown colony on bird seed agar.

The egg shown below may cause perianal itching and is easily passed from one person to another. The egg is 55 x 26 um. Identify this organism. a. Ancylostoma duodenale b. Ascaris lumbricoides c. Enterobius vermicularis d. Trichuris trichuria

c. Enterobius vermicularis

Large one-celled smooth to tuberculate macroconidia and smooth or echinulate micro conidia are typical of the mycelial phase growth in which organism and what Saprophyte has a similar morphology? a. Blastomyces dermatitides, Candida glabrata b. Coccidioides immitis, Alternaria c. Histoplasma capsulatum, Sepedonium d. Paracoccidioides brasiliensis, Penicillium

c. Histoplasma capsulatum, Sepedonium This is the microscopic growth pattern of the mold phase of Histoplasma capsulatum grown at room temperature. Sepedonium is a saprophyte that has a similar microscopic morphology but will not convert to a yeast phase at 35-37 C as Histoplasma capsulatum will.

Several children in a second grade classroom developed tinea capitis. Under a Wood's lamp, their infected hair showed a bright green fluorescence. Cultures of these hairs grew fungi with aerial mycelia, pectinate hyphae and terminal chlamydospores. These isolates are most probably: a. Candida albicans b. Epidermophyton floccosum c. Microsporum audouinii d. Microsporum gypseum

c. Microsporum audouinii Microsporum causes epidemic ringworm of the scalp. The vegetative form of the organism's mycelium shows chlamydospores, favic chandeliers and racquet or pectinate hyphae more commonly than macroconidia.

Which of the following species of Mycobacterium may be presumptively identified by demonstrating a positive niacin reaction? a. Mycobacterium avium-intracellulare complex b. Mycobacterium bovis c. Mycobacterium tuberculosis d. Mycobacterium kansasii

c. Mycobacterium tuberculosis

Which malarial organism, shown below, features ring trophozoites that have double chromatin dots, applique forms, and often have multiple parasites in the infected red cells? a. Plasmodium vivax b. Plasmodium malariae c. Plasmodium falciparum d. Plasmodium ovale

c. Plasmodium falciparum

The formation of arthroconidia is a characteristic of all of the following EXCEPT: a. Coccidioides immitis b. Geotrichum sp. c. Sporothrix schenckii d. Aureobasidium sp.

c. Sporothrix schenckii The only 1 of the four organisms listed that doesn't produce arthroconidia is Sporthrix schenckii. Sporothrix grows in the mold phase as delicate hyphael elements with sleeve-like arrangement of oval microconidia and flowerettes. In the yeast phase Sporothrix forms cigar body yeast cells.

Which parasitic organism causes "autoinfection" or "hyperinfection syndrome"? a. Enterobius vermicularis b. Taenia solium c. Strongyloides stercoralis d. Ancylostoma duodenale

c. Strongyloides stercoralis

Persistent athlete's foot plagues a local basketball team during training season. Upon culture, the organism is found to grow in 12 days on Sabouraud's Dextrose Agar as a fluffy snowy-white velvety colony. There is no distinguishing reverse pigment. Rare, long, narrow thin-walled macroconidia are seen on microscopic preparation. Thin, clavate, tear-drop shaped microconidia are borne laterally from the hyphal elements. Based on this data, a likely etiologic agent is: a. Microsporum audouinii b. Microsporum canis c. Trichophyton mentagrophytes d. Trichophyton rubrum

c. Trichophyton mentagrophytes The large number of microconidia points to a Trichophyton species. There was no reverse red pigment and only an occasional long thin macroconidia. This fits the description of T. mentagrophytes.

Virus particles may be composed of all EXCEPT: a. RNA b. DNA c. both RNA and DNA d. proteins

c. both RNA and DNA

The purpose of 10% potassium hydroxide in the direct examination of skin, hair and nail scraping is to: a. preserve fungal elements b. kill contaminating bacteria c. clear and dissolve debris d. fix the preparation for subsequent staining

c. clear and dissolve debris

Viruses have been successfully detected by the use of all of the following except: a. electron microscopy (EM) b. PCR c. growth on selective agar media d. cytopathic effect (CPE) e. enzyme-linked immunosorbent assay (ELISA)

c. growth on selective agar media

The retrovirus responsible for causing acquired immune deficiency syndrome (AIDS) is known by the name: a. herpes simplex virus-1 b. Epstein-Barr virus c. human immunodeficiency virus d. cytomegalovirus

c. human immunodeficiency virus

The characteristic morphology of Cryptococcus neoformans in specimen is best observed by: a. acid-fast preparation b. Giemsa stain c. negative contrast stain such as an India ink prep b. lactophenol cotton blue

c. negative contrast stain such as an India ink prep Crytococcus neoformans can be seen - usually from sputum specimens - in India Ink Preps as a thick walled encapsulated yeast.

Herpes simplex virus (HSV) causes rapidly fatal infections in: a. elderly patients b. diabetics c. neonates d. sexually active women

c. neonates

This virus can be detected both by use of an electron microscope or by ELISA method. It usually causes GI symptoms in children. Identify the most likely organism. a. respiratory syncytial virus b. influenza A c. rotavirus d. herpes simplex 1

c. rotavirus

The Togavirus known to produce fetal defects is: a. varicella b. rotavirus c. rubella d. influenza

c. rubella

A specimen for viral culture is collected on Friday and must be held for processing until Monday. In GENERAL, the optimal temperature for holding this specimen is: a. 35 C b. 5 C c. -20 C d. -70 C

d. -70 C

This is the largest round worm infection of man. Eggs are round to oval, 45 x 65 um, with an outer, bile-stained mamillated coat and thick inner hyaline shell; larva may be seen in the interior of the egg; decorticated eggs may be present in clinical specimens. What is the genus species of this organism? a. Trichuris trichiura b. Trichinella spiralis c. Necator americanus d. Ascaris lumbricoides

d. Ascaris lumbricoides

Thick walled yeast cells bearing single buds attached by a broad base are observed in an aspirated sputum specimen. The etiologic agent is most likely: a. Candida albicans b. Cryptococcus neoformans c. Geotricum candidum d. Blastomyces dermatitides

d. Blastomyces dermatitides This is the yeast phase of Blastomyces dermatitides as seen in the body in sputum specimens and also as grown outside the body at a temp of 35-37 C. Blastomyces dermatitides is a dimorphic fungi that has two phases - a mold and a yeast phase. The pathogen is always in the yeast phase in the body.

A patient from the North Rim of the Grand Canyon is brought to the emergency room with febrile septicemia and relapsing fever. The patient had been camping in the area for one week and had several tick bites. Blood cultures are taken at five-hour intervals for two days. The microbiologist in the lab performs thick smears and stains with the Giemsa stain. What is the most probable etiological agent? a. Borrelia parkeri b. Treponema pallidum c. Brucella abortus d. Borrelia recurrentis

d. Borrelia recurrentis

Which of the following pair of yeast species is correctly matched with its identifying characteristics? a. Cryptococcus neoformans; urease-negative, encapsulated b. Candida albicans; germ-tube - negative, chlamydospore producer c. Candida glabrata; urease-positive, arthroconidia producer d. Geotrichum species; hyphae producer, arthroconidia producer

d. Geotrichum species; hyphae producer, arthroconidia producer Not Cryptococcus neoformans - C. neoformans is urease +. Not Candida albicans - C. albicans is germ tube +. Not Candida glabrata - C. glabrata is urease neg and does not produce arthroconidia but it is treahalose +. It is Geotrichum spp. - Geotrichum produces true hyphae and the hyphae form arthroconidia.

This organism produced dandruff-like scales on the skin which fluoresce pale yellow under a Woods lamp. This organism has also been found as an infectious agents in lipid infusions. Microscopic examination of the organism reveals clusters of thick-walled, round to oval cells and many short, straight or angular hyphae. This organism is most likely: a. Microsporum gypseum b. Epidermophyton floccosum c. Exophila werneckii d. Malassezia furfur

d. Malassezia furfur Malassezia furfur causes a scaly skin infection called tinea versicolor. It also grows as a yeast form in oils such as olive oil. In the mold phase it has round conidia and short bent hyphal elements that take on a "spaghetti and meatball" morphology.

The presence or absence of a sheath on a microfilaria seen in a peripheral blood smear is an important clue to species identity. This organism is usually diagnosed with a skin snip. In which of the following tissue nematodes are the microfilariae NOT sheathed? a. Brugia malayi b. Loa loa c. Wuchereria bancrofti d. Onchocerca volvulus

d. Onchocerca volvulus

This dimorphic fungus typically has a tissue phase in which the large mother cells have one to a dozen narrow-necked buds often arranged in what is known as a mariner's wheel configuration and a slow-growing mycelial form with intercalary chalmydoconidia and coiled hyphae. What is the identification of this organism? a. Blastomyces dermatitides b. Coccidioides immitis c. Histoplasma capsulatum d. Paracoccidiodes brasiliensis

d. Paracoccidiodes brasiliensis This is the yeast phase of Paracoccidiodes brasiliensis which grows in the body and can be seen in expectorated sputum but also grows on SAB and BHI agar in the lab at 35-37 C. This yeast form is sometimes referred to as a Mariner's Wheel in which multiple daughter yeast cells arise from a single mother cell. This organism grows as a mold phase at room temperature.

A malarial organism presents as a very amoeboid ring trophozoite, often enclosed in a large pale speckled red cell. What is the genus and species of this organism? a. Plasmodium ovale b. Plasmodium malariae c. Plasmodium falcipaum d. Plasmodium vivax

d. Plasmodium vivax

Which malarial organism most likely invade reticulocytes? a. Plasmodium ovale b. Plasmodium falciparum c. Plasmodium malariae d. Plasmodium vivax

d. Plasmodium vivax

Most of the fungi listed below have septate hyphae. Select the one that DOES NOT have septa. a. Alternaria b. Curvularia c. Helminthosporium d. Rhizopus

d. Rhizopus The Zygomycetes have aseptate hyphae. and cause zygomycosis. Mucor and Rhizopus are most commonly associated with disease, Absidia is in this group but less commonly causes infection. Other Zygomycetes include Cunninghamella, Rhizomucor and Syncephalastrum.

A veteran returning from Vietnam is diagnosed as having scrub typhus. The Weil-Felix reaction shows positive agglutination with Proteus OX-K only. What is the organism? a. Rickettsia akari b. Rickettsia prowazekii c. Rickettsia rickettsii d. Rickettsia tsutsugamushi

d. Rickettsia tsutsugamushi

A saprobe which can be easily confused with Histoplasma capsulatum in the mold phase at 25 C is: a. Fusarium b. Penicillium c. Curvularia d. Sepedonium

d. Sepedonium

A rose gardener pricked himself with a contaminated thorn. A subcutaneous fungal infection characterized by the development of necrotic ulcers followed this direct inoculation of fungal spores into the skin. The causative fungus was cultured as a small yeast form at 36 C and as a mold at room temperature with delicate hyphae and conidia in a sleeve-like arrangement. The disease associated with this organism is: a. Blastomycosis b. Chromoblastomycosis c. Myecetoma d. Sporotrichosis

d. Sporotrichosis The organism causing sporotrichosis is Sporothrix schenkii. It is a dimorphic fungi that infects along the lymphatic tract of the arms and legs. In the body and on culture media at 35-37 C, it grows as a yeast forming cigar shaped yeast bodies. The mold phase at room temperature grows as a small oval to tear-drop conidia forming flowerettes, and sleeve-like arrangement of the conidia. Individuals who are immunocompromised ("beer and bricks") are more susceptible to this organism which comes from the prick of rose thorns and hay.

The target of the virus believed to cause acquired immune deficiency syndrome (AIDS) is the: a. B lymphocyte b. hepatocyte c. granulocyte d. T helper cell

d. T helper cell

Trichophyton rubrum and Trichophyton mentagrophytes may BEST be differentiated by: a. the consistently different appearance of their colony morphology b. an endothrix hair infection produced by T. rubrum but not T. mentagrophytes c. the fluorescence of hairs infected with T. rubrum but not hairs infected with T. mentaqgrophytes d. a positive in vitro hair penetration by T. mentagrophytes but not by T. rubrum

d. a positive in vitro hair penetration by T. mentagrophytes but not by T. rubrum The hair penetration test is performed by growing the Trichophyton isolate in a petri disk with sterile child's hair and saline. Allow the fungus to grow for 14-21 days and then examine the hair shaft. T. mentagrophytes invades the hair shaft and forms wedge-shaped hair perforations. T. rubrum does not penetrate the hair and grows only on the surface of the hair strand. T. mentagrophytes produces a red-brown to red-orange reverse pigment and T. rubrum produces a wine-red reverse pigment so the two species can appear somewhat similiar on agar.

Chagas disease: a. is caused by Trypanosoma cruzi b. is characterized by C-shaped typanosomes in the blood c. affects the cardiac muscle d. all of the above

d. all of the above

Hepatitis B virus can be transmitted by: a. acupuncture b. tattoos c. sexual contact d. all of the above

d. all of the above

Four types of fungal structures are sclerotic bodies, philaphora type sporulation, rhinocladiella type sporulation, and cladosporium type sporulation. Which are associated with the causative agents of chromomycosis? a. sclerotic bodies and rhinocladiella-type sporulation b. philaphora type sporulation and cladosporium type sporulation c. philaphora type sporulation, rhinocladiella type sporulation, and cladosporium type sporulation d. all of the above

d. all of the above All of these structures are associated with chromoblastomycosis. Sclerotic bodies - found in the tissue phase of the infection. Philaphora type sporulation found in Phialophora spp. Rhinocladiella-type sporulation found in Fonsecaea spp. Cladosporium-type sporulation found in Cladosporium spp.

Which specimen would be suitable for demonstration of the Trypanosomes of sleeping sickness? a. blood b. fluid form a lymph node c. cerebrospinal fluid d. all of the above could be used

d. all of the above could be used

Which of the following is found infective within the reticuloendothelial cells? a. Leishmania donovani b. Histoplasma capsulatum c. Toxoplasma gondii d. all of these can be found in the R-E cells

d. all of these can be found in the R-E cells

The most common viral syndrome of pericarditis and myocarditis and pleurodynia (pain upon breathing) is caused by: a. herpes simplex b. respiratory syncytial virus c. Epstein-Barr virus d. coxsackie B virus

d. coxsackie B virus

The tubular cells of the human kidney shed which of the following viruses for prolonged periods? a. Epstein-Barr virus b. adenovirus c. rubella virus d. cytomegalovirus

d. cytomegalovirus

The polioviruses, coxsackie viruses, and echoviruses belong to the genus: a. rhinovirus b. poxvirus c. arbovirus d. enterovirus

d. enterovirus

Cerebrospinal fluid from a 24 year old man reveals a high number of mononuclear cells and a negative routine culture for bacteria. Spinal fluid glucose, and protein values are normal. In addition, the patient has vesicular genital lesions. The most likely etiologic agent is: a. Neisseria meningitidis b. enterovirus c. Chlamydia trachomatis d. herpes simplex virus

d. herpes simplex virus

The appearance of Koplik sports in the oral mucosa of patients is characteristic of infection with what viral agent? a. rabies b. yellow fever c. dengue fever d. measles

d. measles

Which virus is associated with venereal and respiratory tract warts and produces lesions of skin and mucous membranes? a. polyomavirus b. poxvirus c. adenovirus d. papillomavirus

d. papillomavirus

A very small, single-stranded DNA virus that causes a febrile illness with a rash and is called the fifth childhood disease after rubeola, rubella, varicella, and roseola is: a. rotavirus b. adenovirus type 40 c. coxsackie A virus d. parvovirus B19

d. parvovirus B19

The most useful finding for prompt, presumptive identification of Candida albicans is its: a. failure to assimilate sucrose b. "feathering" morphology on EMB Agar c. production of chlamydospore on cornmeal agar d. production of germ tubes in rabbit plasma

d. production of germ tubes in rabbit plasma The germ tube test uses rabbit or human plasma. The yeast is incubated in 0.5 ml of plasma for 2 hours and examined for the production of germ tubes. Germ tubes are a filamentous extension of a yeast blastoconidia that is about half the width and 3-4 times the length of the cell. A true germ tube has no constriction at its point of origin. The most frequently positive isolate with the Germ Tube test is Candida albicans. However Candida dubliniensis also forms germ tubes, and like C. albicans produces Chalymdospores. Maldi-tof is now able to readily differentiate C. albicans from C. dubliniensis. Candida tropicalis can give a false positive germ tube test which is really a pseudohyphae and if one looks closely, the extension is constricted at its point of origin.

Kaposi's sarcoma and B cell lymphomas are highly associated with what infectious group of viral agents? a. reoviridae b. picornaviridae c. parvoviridae d. retroviridae

d. retroviridae

The majority of the common cold viruses are classified as: a. echoviruses b. adenoviruses c. rotoviruses d. rhinoviruses

d. rhinoviruses

In tissue infected with Histoplasma capsulatum: a. the hyphae can be seen invading blood vessels b. encapsulated budding yeast cells are the typical infective form c. tuberculate macroconidia are the typical infective form d. the yeast phase can be seen growing intracellularly within macrophages

d. the yeast phase can be seen growing intracellularly within macrophages This is the yeast phase of Histoplasma capsulatum that grows in the body in cells of the RES system which includes macrophages. The oval yeast cells can be seen clearly.

Athlete's foot is most often caused by either Trichophyton mentagrophytes or Epidermophyton floccosum. This superficial mycosis is also commonly referred to as: a. tinea capitis b. tinea unguium c. tinea versicolor d. tinea pedis

d. tinea pedis Tinea capitis = ringworm of the head Tinea unguium = ringworm of the nails Tinea versicolor = ringworm of the skin Tinea pedis = athlete's foot