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School of Molecular & Biomedical Science
The University of Adelaide
AUSTRALIA 5005

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Dr David Ellis
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Exophiala dermatitidis

Synonym: Wangiella dermatitidis
Synanamorph: Phaeococcomyces exophialae

Colonies are slow growing, initially black and yeast-like, becoming suede-like, olivaceous grey and mould-like with age. The initial yeast-like phase is referred to as the Phaeococcomyces exophialae synanamorph, which is characterized by unicellular, ovoid to elliptical, budding yeast-like cells. The yeast-like cells are hyaline and thin-walled when young and becoming darkly pigmented (dematiaceous) and thick-walled when mature. With the development of mycelium or the mould-like stage, flask-shaped to cylindrical phialides without distinctive collarettes are produced. Conidia are hyaline to pale brown, one-celled, round to obovoid, 2.0-4.0 x 2.5-6.0 um, smooth-walled and accumulate in slimy balls (glioconidia) at the apices of the phialides or down their sides.  Cultures grow at 42C.  RG-2 organism.

Phialides and conidia
Phialides and conidia of Exophiala dermatitidis.

 

MIC data is limited.  Antifungal susceptibility testing of individual strains is recommended.

Antifungal MIC ug/mL Antifungal
MIC ug/mL
Range
MIC90
Range
MIC90
Itraconazole
0.03-2
0.5
Amphotericin B
0.03-2
0.5
Voriconazole
0.06-0.25
0.125
Posaconazole
0.03-1
nd

 

Clinical significance:

Exophiala dermatitidis has been isolated from plant debris and soil and is a recognized causative agent of mycetoma and phaeohyphomycosis in humans. Clinical manifestations include subcutaneous cystic lesions, endocarditis and brain abscesses. E. dermatitidis is neurotropic and cerebral infections are frequently seen.

Mycosis: Phaeohyphomycosis

Further reading:

De Hoog, G.S., and E.J. Hermanides-Nijhof. 1977. The black yeasts and allied hyphomycetes. Studies in Mycology No. 15. Centraalbureau voor Schimmelcultures, Baarn, The Netherlands.

Kwon-Chung, K.J. and J.E. Bennett. 1992. Medical Mycology. Lea & Febiger, Philadelphia and London.