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What are the 4 major subcutaneous infections caused by fungi?
- 1. Mycetoma
- 2. Chromoblastomycosis
- 3. Phaeohyphomycosis
- 4. Sporotrichosis (see dimorph lect. for info)
Common to all discription of subcutaneous infections
Lesion develops at site of inoculation.
Soil saprohytes - Moderately slow growers
Common in tropics and subtropics
What are some common organisms that cause many of these subcutaneous infections?
Define dematiaccous fungi - This is common with subcutaneous infections.
It can produce melanin and appeard dark pigmented.
*Hyaline fungi is clear
Subcutaneous fungi exhibit 3 types of conidiation (microscopic view) on how fungi reporduce asexually from spores.
Name all 3
Describe cladosporium conidiation
Resembles a tree, where conidiophore is the trunk and branched chains of conidia form the branches.
Describe phialophora conidiation
Short conidiophores + phialide, vase shaped, conidia extrude from phialide and then cluster.
Describe rhinocladiella conidiation
Stalked conidiophores that become knobby as conidia are produced, conidia produced sequentially until a cladosporium type conidiation is reached.
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
Describe Mycetoma infection
Chronic Granulomatous disease of lower extremities
Exudate contains granules
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
What are two etiologic agents of Mycetoma?
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
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
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
Describe Cladophialophora carrioinii clinical disease & lab ident.
- Macro:SLOW (up to 30 days), grey-green to black
- Reverse: cottony
Micro: PIgmented septate hyphae & Cladosporium type conidiation
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
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
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
Disease & Lab Ident
- 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
Pseuallescheria boydii aka Scedosporium apiospermun
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)
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
Sporothrix schenckii disease
cutaneous and subcutaneous inf.
*Rose gardeners disease*
Sporothrix schenckii lab info
Bx tissue or pus
- Mould in 3-5 days at 25C
- Mature colonies are dark and flat
- Yeast at 37C in 3-5 days
- White or tan
- Mould - Delicate thin hyphae, septate, frequently found as ropes, conidiophores produce multiple conidia in flowerette arrangements.
- *Conidia seen as small oval unicellular
- *Large dark walled spheres
- Cigar shaped at 37C
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