MV Flashcards
The most useful finding for prompt, presumptive identification of C. albicans is its:
Failure to assimilate sucrose
Feathering on EMB
Production of chlamydospores
Production of germ tubes
Production of germ tubes
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Essentially all strains of Candida albicans produce germ tubes within 2 hours of incubation at 37°C in serum.
Germ tube formation is seen with which two yeasts?
C. albicans, C. neoformans
C. albicans, C. parapsilosis
C. glabrata, C. parapsilosis
C. albicans, C. dubliniensis
C. albicans, C. dubliniensis
The formation of arthroconidia is not an important characteristic in the identification of:
Coccidioides
Geotrichum
Trichosporon
Sporothrix
Sporothrix
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Sporothrix is the sole member of the list that does not produce arthroconidia.
A black pigment produced by colonies growing on bird seed agar is due to:
Urease
Phenol oxidase
Sucrose assimilation
Arthroconidia production
Phenol oxidase
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Phenol oxidase breaks down the substrate found in niger seeds producing melanin. This result is characteristic of C. neoformans.
What are the optimal temperature and incubation time before a fungal blood culture is reported as negative?
37°C; 21 days
37°C; 7 days
30°C; 21 days
30°C; 7 days
30°C; 21 days
Which group of molds can be ruled out when septate hyphae are observed in a culture?
Dematiaceous
Zygomycetes
Dermatophytes
Dimorphic molds
Zygomycetes
Tinea versicolor is a skin infection caused by:
Malassezia furfur
Trichophyton rubrum
Trichophyton schoenleinii
Microsporum gypseum
Malassezia furfur
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M. furfur has a worldwide distribution and causes a superficial, brownish, dry, scaly patch on the skin of light-skinned persons and lighter patches on persons with dark skin.
Dry, horny, platelike lesions or SCALES are associated with:
Dermatophytes (tinea)
Sporothrix schenckii
Mycobacterium marinum
Varicella-zoster virus
Dermatophytes (tinea)
Adding specimen scrapings to 10% KOH to show the presence of SCLEROTIC BODIES that resemble COPPER PENNIES is useful in the diagnosis of:
Chromoblastomycosis
Phaeohyphomycosis
Mycetomas
Zygomycosis
Chromoblastomycosis
A thermally dimorphic fungus shows a filamentous mold form with TUBERCULATE MACROCONIDIA at room temperature, and a yeast form above 35°C. Which organism best fits this description?
Histoplasma capsulatum
Paracoccidioides brasiliensis
Candida albicans
Coccidioides immitis
Histoplasma capsulatum
The yeast form of which dimorphic mold shows a large parent yeast cell surrounded by smaller budding yeast cells?
Paracoccidioides brasiliensis
Sporothrix schenckii
Coccidioides immitis
Histoplasma capsulatum
Paracoccidioides brasiliensis
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P. brasiliensis yeast forms are sometimes seen as a “mariner’s wheel” because multiple budding cells completely surround the periphery of the parent cell.
A 2-month-old infant in good health was scheduled for a checkup at the pediatrician’s office. After arriving for the appointment, the mother noted white patches on the baby’s tongue and in his mouth. The baby constantly used a pacifier. What is the most likely organism causing the white patches?
Cryptococcus neoformans
Candida albicans
Aspergillus fumigatus
None of these options
Candida albicans
An India ink test was performed on CSF from an HIV-infected male patient. Many encapsulated yeast cells were seen in the centrifuged sample. Further testing revealed a positive urease test and growth of brown colonies on niger-seed agar. The diagnosis of meningitis was caused by which yeast?
Candida albicans
Cryptococcus neoformans
Cryptococcus laurentii
Candida tropicalis
Cryptococcus neoformans
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Immunocompromised patients are at risk for invasion of Cryptococcus neoformans. The polysaccharide capsule of C. neoformans is not recognized by phagocytes, which allow patients with impaired cell-mediated immunity to become readily infected with C. neoformans.
The appearance of Koplik spots in the oral mucosa of patients is characteristic of infection with what viral agent?
Hepatitis
Measles
Rabies
Smallpox
Measles
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Koplik spots are diagnostic for measles infection and represent necrotic vesicles with a white center surrounded by erythema.
Kaposi sarcoma is associated with infection by:
Adenovirus
Cytomegalovirus
Hepatitis E vims
Human herpes virus 8
Human herpes virus 8
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Kaposi sarcoma, a relatively common cancer in patients with AIDS, has been linked to human herpes virus 8.
Negri bodies may be found in brain tissue of humans or animals infected with:
Adenovirus
Filovirus
Measles virus
Rabies virus
Rabies virus
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Rabies is a neurotropic virus that causes extensive destruction in the brain. Negri bodies are seen in the cytoplasm of large ganglion cells and are demonstrated by Seller’s stain. Rabies in humans or lower animals can be diagnosed by demonstration of these characteristic inclusions.
The virus associated with warts is:
Flavivirus
Morbillivirus
Mumps virus
Papillomavirus
Papillomavirus
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The etiologic agents for the numerous benign cutaneous and mucosal lesions known as warts are the human papillomaviruses (HPVs).
A dehydrated 25-year-old male patient was admitted to the hospital with SYMPTOMS SIMILAR TO THOSE OF CHRONIC FATIGUE SYNDROME. Serological testing proved negative for recent streptococcal infection, Epstein–Barr virus, and hepatitis. Which of the following viral serological tests should help with a possible diagnosis?
CMV
Echovirus
Respiratory syncytial virus
Measles virus
CMV
Collection of specimens from cutaneous vesicles for detection of these viruses may require a TZANCK SMEAR:
CMV and EBV
HSV and VZV
JC and BK polyomavirus
HBV and HCV
HSV and VZV
Transient aplastic crisis can occur with:
Parvovirus B19
West Nile virus
Cytomegalovirus
Epstein Barr virus
Parvovirus B19
The filovirus that has a characteristic “shepherd’s hook” morphology when viewed by electron microscopy is:
Ebola Zaire virus
Ebola Reston virus
Ebola Sudan virus
Marburg virus
Marburg virus
Slow but continuing replication of damaged virus in the brain gives rise to SUBACUTE SCLEROSING PANENCEPHALITIS:
Measles virus
Mumps virus
Parainfluenza virus
Respiratory syncytial virus (RSV)
Measles virus
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Subacute sclerosing panencephalitis (defective measles virus infection of CNS).
Most common cause of ASEPTIC MENINGITIS, an inflammation of the brain parenchyma:
Arenavirus
Cytomegalovirus
Enterovirus
Herpes simplex virus 2
Enterovirus
A 3-year-old female was admitted to the hospital following a 2-day visit with relatives over the Christmas holidays. Vomiting and diarrhea left the child severely dehydrated. No other members of the family were affected. All bacterial cultures proved negative. A stool sample should be tested for which virus?
Adenovirus
CMV
Hepatitis D
Rotavirus
Rotavirus
Which of the following viruses is implicated along with Epstein–Barr virus as a cause of infectious mononucleosis?
Cytomegalovirus (CMV)
Coxsackie A virus
Coxsackie B virus
Hepatitis B virus
Cytomegalovirus (CMV)
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CMV infection in a previously healthy individual causes a self-limited mononucleosis syndrome
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:
Rotavirus
Adenovirus type 40
Coxsackie A virus
Parvovirus B19
Parvovirus B19
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Parvovirus causes a fever and characteristic “slapped cheek” rash in young children. Adults are usually immune, but immunocompromised persons may exhibit an arthritis or anemia (the virus infects immature RBCs in the bone marrow).
All of the following are examples of appropriate specimens for the recovery of fungi except:
Tissue biopsy
CSF
Aspirate of exudate
Swab
Swab
Specimens for fungal culture must be kept in a moist, sterile environment. Swabs that are dried out or submitted with insufficient material on them should be rejected.
What are the optimal temperature and incubation time before a FUNGAL BLOOD CULTURE is reported as negative?
37°C; 21 days
37°C; 7 days
30°C; 21 days
30°C; 7 days
30°C; 21 days
For which clinical specimens is the KOH direct mount technique for examination of fungal elements used?
Skin
CSF
Blood
Bone marrow
Skin
A solution of 10% KOH is used for contaminated specimens such as skin, nail scrapings, hair, and sputum to clear away background debris that may resemble fungal elements.
Which group of molds can be ruled out when septate hyphae are observed in a culture?
Dematiaceous
Zygomycetes
Dermatophytes
Dimorphic molds
Zygomycetes
Zygomycetes commonly recovered from clinical specimens are Rhizopus spp. and Mucor spp. Both display ASEPTATE HYPHAE, while the other groups above display septate hyphae.
Tinea versicolor is a skin infection caused by:
Malassezia furfur
Trichophyton rubrum
Trichophyton schoenleinii
Microsporum gypseum
Malassezia furfur
Cutaneous mycoses are fungal infections that involve:
Hair
Skin
Nails
All of the above
All of the above
A Wood’s lamp is used to detect fluorescing hairs in which dermatophyte?
M. audouinii
M. canis
M. gypseum
M. audouinii, M. canis
M. audouinii, M. canis
M. audouinii: fluoresce yellow-green under a Wood’s lamp, no growth in rice medium
M. canis :bright yellow-green under a Wood’s lamp, growth in rice medium
Which test can be used to differentiate T. mentagrophytes from T. rubrum?
Fluorescence using a Wood’s lamp
In vitro hair perforation
Red color on reverse side of colony
Gram staining
In vitro hair perforation
T. mentagrophytes: positive hair baiting and urease test
T. rubrum: negative hair baiting and urease test