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 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.
