Subcutaneous Mycoses

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Subcutaneous Mycoses
2013-12-08 11:30:52
Subcutaneous Mycoses
Subcutaneous mycoses
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  1. What are the 4 major subcutaneous infections caused by fungi?
    • 1. Mycetoma
    • 2. Chromoblastomycosis
    • 3. Phaeohyphomycosis
    • 4. Sporotrichosis (see dimorph lect. for info)
  2. Common to all discription of subcutaneous infections
    Lesion develops at site of inoculation. 

    Soil saprohytes - Moderately slow growers

    Common in tropics and subtropics
  3. What are some common organisms that cause many of these subcutaneous infections?
    Sporothrix shenckii

    • Cladophialophora
    • phialophora
    • Exophiala
    • Fonsecaea
    • Wangiella
    • Pseudoallescheira/Scedosporium
  4. Define dematiaccous fungi - This is common with subcutaneous infections.
    It can produce melanin and appeard dark pigmented.

    *Hyaline fungi is clear
  5. Subcutaneous fungi exhibit 3 types of conidiation (microscopic view) on how fungi reporduce asexually from spores. 

    Name all 3


  6. Describe cladosporium conidiation
    Resembles a tree, where conidiophore is the trunk and branched chains of conidia form the branches.
  7. Describe phialophora conidiation
    Short conidiophores + phialide, vase shaped, conidia extrude from phialide and then cluster.
  8. Describe rhinocladiella conidiation
    Stalked conidiophores that become knobby as conidia are produced, conidia produced sequentially until a cladosporium type conidiation is reached.
  9. Typical lab specimen and testing info
    Specimen is aspiration (large amount = minimal chance of drying out)

    Granules observed and noted.

    • SAB w/&w/o antibiotics
    • PDA for subculture
  10. Describe Mycetoma infection
    Chronic Granulomatous disease of lower extremities

    Exudate contains granules

    Remains localized
  11. Lab procedure and ident for Mycetoma
    KOH - ID of granules: 

    • 2 types seen: 
    • * Actinomycotic granules = mycelium with hyphae 1um in diameter
    • *Eumycotic granules = Wide hyphae (2-4um) terminating in chlamydoconidia

    Pigmented or hyaline septate hyphae
  12. What are two etiologic agents of Mycetoma?
    Exophiala jeanselmei

    Acremonium sp.
  13. Exoophiala jeanselmei

    Disease and lab ident
    Causes Mycetoma and phaehyphomycosis from trauma or **contaminated fomites

    • Macro: Young appear as black yeast
    •           Mature are velvety 

    Micro: Strick-like conidiophores with clustered conidia. Develop true hyphae
  14. Describe Chromoblastomycosis infection
    skin and subcutaneous tissue

    Wart-like (verrucoid) lesions on feet, legs, hands, and buttocks

    Spreads through body lymphatics or by autoinoculation

    • Soil saprhytes
    • worldwide
    • dematiacious
  15. Lab procedure and ident for Chromoblastomycosis
    KOH (use crust or exudate from lesion)

    Micro: single celled sometimes in clusters, dark pigmentation seen

    Culture: SAB - Rm. Temp - 6 weeks

    May produce all types of conidiation
  16. Describe Cladophialophora carrioinii clinical disease & lab ident.
    Causes chromoblastomycosis

    • Macro:SLOW (up to 30 days), grey-green to black
    • Reverse: cottony

    Micro: PIgmented septate hyphae & Cladosporium type conidiation
  17. Describe Fonsecaea pedrosoi clinical and lab ident.
    Causes chromoblastomycosis & may lump into phaeohyphomycosis.

    Macro: Mod (within 21 days) Grey-green to black, cottony

    Micro: Pigmented sepatate hyphae & all 3 types of conidiation seen: phialophora, cladosporium, & rhinocladiella
  18. Describe Phialophora verrucosa clinical and lab ident.
    Causes chromoblastmycosisi and phaeohyphomycosis via trauma or autoinoculation and lymphatic system.

    Macro: Olive-green to black, vlevety

    • Micro: Pigmented septate hyphae
    • ** ONLY phialophora type conidiation
  19. Phaeohyphomycosis

    Does not belong to the typicall fungi. This is a miscelaneous that doesn't fit anywhere else....

    Consists of a group of mycotic infections characterized by the presence of dematiaceous (dark-walled) septate hyphae and sometimes yeast or a combination of both in tissue. Hyphae and yeast will vary in size and shape.

    KOH shows pigmented hyphae
  20. Wangiella dermatitidis

    Disease & Lab Ident
    Causes pheophyphomycosis

    • Macro: Initially resembles black yeast
    •           >10days, olive greay to black velvety or glabrous 
    •           *Grows best at 40-42C

    Micro: Pigmented spetate hyphae, conidiophores are indistinguishable from vegative hyphae, except that conidia are clustered at the ends.

    **Temp will help distinguish from E. jeanselmei
  21. Pseuallescheria boydii aka Scedosporium apiospermun

    Lab Ident
    Is not a demateaceous**

    **Major etiologic agent of mycetoma in the US and Europe

    Macro: RAPID*, hyaline, sexual form, white to brownish greay, & fluffy

    Microscopic: Hyaline sepatate hyphae

    Single anelloconidia produced on an anellophore (conidiophore)
  22. Madurella sp.

    Name 2 and lab info
    • M. grisea:
    • **Macro: folded in center with radial grooves, dark gray to olive brown, reverse is dark
    • **Micro: Dark thick hyphaeother structures may be absent

    • M. mycetomatis: 
    • **Macro: slow, fluffy white, grows best at 37C, reverse is dark
    • **Micro: same as M. grisea

    No need to differentiate
  23. Sporothrix schenckii disease
    Causes sporotrichosis

    cutaneous and subcutaneous inf.

    *Rose gardeners disease*

    Soil Saprobe
  24. Sporothrix schenckii lab info
    Thermally dimorph

    Bx tissue or pus

    • Macro: 
    • Mould in 3-5 days at 25C
    • Mature colonies are dark and flat

    • Yeast at 37C in 3-5 days 
    • White or tan

    • Micro:
    • Mould - Delicate thin hyphae, septate, frequently found as ropes, conidiophores produce multiple conidia in flowerette arrangements.
    • *Conidia seen as small oval unicellular 
    • or
    • *Large dark walled spheres

    • Yeast: 
    • Cigar shaped at 37C