Microbiology Lab Quiz: Fungi and Dermatophytes

Study Notes

Mycosel medium is used to grow dermatophytes, and it contains chloramphenicol to inhibit bacteria and cycloheximide to inhibit fungal contaminants.
Czapek's medium is used to grow Aspergillus.
Germ tubes form at 35°C and are characteristic of yeasts.

Candida is a type of fungus that is Gram-positive, and its cells are oval-shaped with or without buds and pseudomycelia.
Candida albicans is a type of Candida that causes thrush, diaper rash, and moniliasis.

SDA (Sabouraud Dextrose Agar) is a general culture medium for fungi.
Cornmeal agar is used to grow Candida albicans and to identify Chlamydospores.
Hair baiting test is used to isolate Trichophyton mentagrophytes.
10% KOH is used for direct microscopic examination and clearing of skin and hair samples.
LPCB (Lactic acid, Phenol, and Cotton blue) is a commonly used stain for fungal cultures.
Calcofluor white is a fluorescent dye that stains the chitin in fungal cell walls.

Hyphae are the basic structure of fungi and can be septate or aseptate.
Spores are reproductive structures that can be sexual (ascospores, basidiospores, oospores) or asexual (chlamydospores, blastospores, conidia, arthrospores).
Conidiophore is a structure that produces conidia, and sporangiophore is a structure that produces spores.

Dermatophytes infect the skin, hair, and nails, and they produce macroconidia and microconidia.
Trichophyton infects hair, skin, and nails, and it has a teardrop-shaped conidia.
Trichophyton rubrum has a red color and produces teardrop-shaped conidia.
Trichophyton schoenleinii has a favic chandelier-shaped structure.

H.capsulatum is a dimorphic fungus that can be identified using Wright's/Giemsa stain.
C.immitis is a high-risk fungus for lab personnel.

Amphotericin B is a fungicidal agent that targets ergosterol in fungal cell membranes.
Azole (Fluconazole) is a fungistatic agent that inhibits fungal growth.