Superficial mycoses

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  1. Define tineas
  2. Define piedras
  3. Superficial mycoses are usually cultured onto what?
    Sabourad Dextrose agar

    * Sometimes with abtibiotics
  4. What are the 4 main superficial mycoses?
    • Tinea (skin) versicolor
    • Tinea Nigra
    • White piedra (hair)
    • Black piedra
  5. Tinea veriscolor is caused by what?

    What is the appearance on skin?
    • Malassezia furfur
    • Patches of pigmented brownish colored lesions. upper body. Itch burn
  6. 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.
  7. What and where is Tinea Nigra caused by?
    Hortaea weneckii

    USA, SE Asia, Africa, Europe (enviromental)
  8. 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.
  9. 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
  10. White Piedra is caused by what spp. and what is the most comon?
    Trichosporon spp.

    *Most common = T. beigelii
  11. 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
  12. 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


    Micro: Many pseudohyphae and hyphae, blastoconidia, *Arthroconidia
  13. Black Piedra is caused by what?
    Piedraia hortae
  14. 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
  15. 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
Card Set
Superficial mycoses
Superficial mycosis
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