14 Questions
What is the medium for dermatophytes?
Mycosel
Which of the following fungi produces ascospores?
S.cerevisiae
What is the method used for direct microscopic examination of skin and hair?
10% KOH
Which of the following is a characteristic of Coenocytic fungi?
Aseptate hyphae
What is the purpose of the hair baiting test?
To diagnose T.mentagrophytes
What is the characteristic of Trichophyton rubrum?
Red color
What is the primary function of hyphae in fungal growth?
Aerial/vegetative/substrate
Which type of fungal cell wall component is stained by Calcofluor white?
Chitin
What is the primary function of dermatophytes?
Keratin degradation
Which type of fungal infection is characterized by a lack of immune response from the host?
Superficial mycoses
What is the primary function of sporangiophore?
Aseptate hyphae formation
Which type of fungal spore is characterized by budding off?
Blastospores
What is the primary function of Giemsa/Wright's stain?
To identify H.capsulatum in blood smears
What is the primary function of Amphotericin B?
Fungicidal agent
Study Notes
Fungi Characteristics
- 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
- 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.
Media and Tests
- 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.
Fungal Structures
- 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
- 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.
Systemic Mycoses
- 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.
Fungicides
- Amphotericin B is a fungicidal agent that targets ergosterol in fungal cell membranes.
- Azole (Fluconazole) is a fungistatic agent that inhibits fungal growth.
Identification Methods
- API20C and ID32C are biochemical tests used to identify fungi.
- CHROMagar is a medium used to identify Candida.
- Germ tube test is used to identify unknown yeast species.
This quiz covers various aspects of microbiology, including fungi, dermatophytes, and laboratory tests used to identify them.
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