Mycology 1 Answers – Flashcards
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Mycology
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- study of fungi (yeasts to mushrooms) - sexual, asexual
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Fungi: Reproduction
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- sexual: spores - asexual: budding conidia
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Hyphae
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- tube-like structures - main mode of vegetative growth
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Septate vs Aseptate (Coenocytic) Hyphae
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Note the cross walls btwn nuclei
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Pseudohyphae: General
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- elongated budding yeast cells (blastoconidia) that remain attached after division with constrictions btwn cells
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Hyphae vs. Pseudohyphae
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- PH: constriction btwn cells (cytoplasm separate) - H: no constriction, shared cytoplasm
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ID the structure
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Pseudohyphae: note constriction btwn cells
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Mycelium
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- mat of hyphae
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Fruiting Bodies
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- sexual: true spores via spore sacs - asexual: spores via conidium, sporangium
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Mycology: Lab Methods
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- 10% KOH: clears debris, breaks down keratin from nails, hair - lactophenol cotton blue: stains, kills org.
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Mycology: Primary growth agar
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- SAB: Sabouraud's dextrose agar - Mycosel: sim. to SAB but inhibits some Candida, Cryptococcus, Aspergillus
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Mycology: Specialty agar
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- bird-seed: C. neoformans - corn meal: C albicans - rice infusion oxgall Tween 80 (RIOT)
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Lab Dx: Brown colonies on bird see agar
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- Cryptococcus neoformans
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Lab Dx: Chlamydospore formation on corn meal agar
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- Candida albicans
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Mycology: Specimen Collection ; Handling
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- 25-30°C for up to 6 wks - use screw cap or tape plates to prevent drying - use the HOOD!
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Dermatophytes: General
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- septate hyphae, conidia - cause tinea (ringworm) - take KOH prep from lesion, hair, or nails
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Wood's Lamp
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- black (UV) light - some dermatophytes (ringworm) fluoresce in UV light
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Tinea capitis: Endo- vs Ectothrix
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- scalp ringworm - endothrix: in shaft, temp hair loss - ectothrix: outside shaft: perm hair loss
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Dermatophytes: Examples
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- Microsporum spp. - Trichophyton spp. - Epidermophyton spp.
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Systemic Mycoses: General
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- opportunistic pathogens: C. neoformans, C. albicans, Aspergillus - dimorphic pathogens: inhaled and spread thru body
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Opportunistic Pathogens: Examples
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- C. neoformans (HIV+) - C. albicans - Aspergillus spp.
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Opportunistic Pathogens: General
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- attack severely immunocompromised patients - Ex: HIV/AIDS, cancer, antibiotic therapy
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Dimorphic Fungi
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- exist as yeast at 36°C, mold at 30°C - incl. primary, systemic pathogens (inhaled)
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Dimorphic Fungi: Pathogens
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- Histoplasma capsulatum - Blastomyces dermatitidis - Coccidioides immitis - Sporothrix schenckii - etc.
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Cryptococcus neoformans: General
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- opportunistic yeast - brown on bird seed (found in bird droppings) - capsule detected w India ink
