SM Mycology & Fungal Diagnostics 3

Question 1

Candida albicans produces chlamydospores (large, thick-walled spores) when grown on which medium used for morphological identification?

Accepted Answer

Cornmeal agar with Tween 80 at 25–28°C

Answer

Germ tube serum medium at 37°C

Answer

CHROMagar Candida at 37°C

Answer

Brain-heart infusion broth

Question 2

The beta-D-glucan assay (e.g., Fungitell) detects which fungal cell wall component as a broad screening test for invasive fungal infection?

Accepted Answer

(1→3)-β-D-glucan

Answer

Chitin

Answer

Ergosterol

Answer

Galactomannan

Question 3

Which morphological feature is used to microscopically distinguish Aspergillus niger from other Aspergillus species?

Accepted Answer

Biseriate phialides bearing dark brown-black conidia on a large globose conidial head

Answer

Uniseriate phialides with white/cream conidia on a small vesicle

Answer

Yellow-green conidia on a long conidiophore with flask-shaped phialides

Answer

Hyaline conidia arranged in chains without a vesicle

Question 4

For optimal selective recovery of dermatophytes from skin or nail specimens, Sabouraud dextrose agar should be supplemented with which combination of inhibitory agents?

Accepted Answer

Cycloheximide and chloramphenicol

Answer

Vancomycin and amphotericin B

Answer

Penicillin and streptomycin only

Answer

Fluconazole and gentamicin

Question 5

Coccidioides immitis and Coccidioides posadasii, the agents of coccidioidomycosis ('Valley Fever'), are endemic to which US geographic region?

Accepted Answer

Arid desert regions of the Southwestern United States

Answer

Pacific Northwest temperate rainforest regions

Answer

Great Lakes region and upper Midwest

Answer

Gulf Coast humid subtropical regions

Question 6

Which biosafety precaution is mandatory when processing or manipulating mold-phase cultures of dimorphic fungi (e.g., Histoplasma capsulatum, Coccidioides immitis)?

Accepted Answer

BSL-3 practices with all manipulations performed in a certified Class II biological safety cabinet

Answer

Standard precautions (gloves and lab coat) at the open bench

Answer

Chemical fume hood with standard gloves only

Answer

N95 respirator at the open bench without a biosafety cabinet

Question 7

Talaromyces (formerly Penicillium) marneffei is a thermally dimorphic pathogen that primarily affects immunocompromised patients in which geographic region?

Accepted Answer

Southeast Asia (particularly Thailand, southern China, Vietnam)

Answer

Sub-Saharan Africa

Answer

Central and South America

Answer

Eastern Europe and Central Asia