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Superficial mycoses are usually cultured onto what?
Sabourad Dextrose agar
* Sometimes with abtibiotics
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What are the 4 main superficial mycoses?
- Tinea (skin) versicolor
- Tinea Nigra
- White piedra (hair)
- Black piedra
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Tinea veriscolor is caused by what?
What is the appearance on skin?
- Malassezia furfur
- Patches of pigmented brownish colored lesions. upper body. Itch burn
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Lab testing for Tinea veriscolor (M. furfur)
KOH - will show yeast like hyphal forms.
Cx will be neg if you do not add an oil overlay and incubate at 37C.
Micro - Thick walled hyphae and some budding yeast.
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What and where is Tinea Nigra caused by?
Hortaea weneckii
USA, SE Asia, Africa, Europe (enviromental)
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What is the appearance of skin for Tinea Nigra?
- Keratinized skin layers of hand
- *common in those <25yrs old
- Darkened flat, brown lesion
**Must be diagnosed to rule out melanoma.
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Laboratory tests for diagnosis of H. werneckii (Tinea Nigra)
Micro - Septate thick wall hyphae, yeast like conidia, chlamydospores (hyaline later turning to olive colored), *Annellides presesnt
Macro - SLOW GROWER, mature in 21 days, pale in color, moist, shiny, and yeast like. They become velvety, olive black and are covered with a thin layer of mycelium.
Reverse is Black
*DO NOT grow at 37C
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White Piedra is caused by what spp. and what is the most comon?
Trichosporon spp.
*Most common = T. beigelii
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What is appearance and disease of White Piedra (T. beigelii)
Infection of hair of beard and mustache.
Soft white tan nodules on hair shaft
*Can actually become systemic
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Laboratory tests for ident of White Piedr / Trichosporon spp.
Direct from sample collected:KOH (Cx & micro uncommon)
Macro: RAPID, yeast like, smooth, wrinkled, raised, folded, white to cream
UREASE = IS POSITIVE
Micro: Many pseudohyphae and hyphae, blastoconidia, *Arthroconidia
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Black Piedra is caused by what?
Piedraia hortae
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Appearance and disease of Black Piedra (Piedraia hortae) and location
Forms black, stony, hard nodules on hair & scalp.
Swimming in rivers and stagnant waters
Central and South America, Southern Asia & Africa
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Lab testing for diagnosis of Piedraia hortae (black piedra)
Direct: KOH, usually not cultured
Macro: SLOW (grows at 25C), small folded, dark brwon to black, may produce a reddish brown pig.
Reverse is Black
- Micro: Septate pigmented hyphae, asci, and ascospores present.
- **Asci are ellipsoid, solitary or in clusters and contain 8 ascospores
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