Exophiala spinifera
Synonym: Phialophora spinifera; Rhinocladiella spinifera
Recent molecular studies have re-examined Exophiala spinifera and have recognised two species: E. spinifera and E. attenuata (Vitale and de Hoog, 2002). These two species are morphologically very similar and can best be distinguished by genetic analysis.
Conidiogenous cells are predominately annellidic and erect, multicellular conidiophores that are darker than the supporting hyphae are present. No growth at 40C.
| E. spinifera | Annellated zones are long with clearly visible, frilled annellations. |
| E. attenuata | Annellated zones are inconspicuous and degenerate. |
Colonies are initially mucoid and yeast-like, black, becoming raised and developing tufts of aerial mycelium with age, finally becoming suede-like to downy in texture. Reverse is olivaceous-black. Conidiophores are simple or branched, erect or sub-erect, spine-like with rather thick brown pigmented walls. Conidia are formed in basipetal succession on lateral pegs either arising apically or laterally at right or acute angles from the spine-like conidiophores or from undifferentiated hyphae. Conidiogenous pegs are 1-3 µm long, slightly tapering and imperceptibly annellate. Conidia are one-celled, subhyaline, smooth, thin-walled, subglobose to ellipsoidal, 1.0-2.9 x 1.8-2.5 µm, and aggregate in clusters at the tip of each annellide. Toruloid hyphae and yeast-like cells with secondary conidia are typically present. No growth at 40C. RG-2 organism.
Conidiophores, annellides and conidia of Exophiala spinifera.
MIC data is limited. Antifungal susceptibility testing of individual strains is recommended.
| Antifungal | MIC ug/mL |
Antifungal | MIC ug/mL |
Antifungal | MIC ug/mL |
Range |
Range |
Range |
|||
| Amphotericin B | 0.125-1 |
Itraconazole | 0.03-1 |
Voriconazole | 0.125-1 |
Clinical significance:
Exophiala species are common environmental fungi often associated with decaying wood and soil enriched with organic wastes. However, several species notably E. jeanselmei, E. moniliae and E. spinifera, are well documented human pathogens. Clinical manifestations include mycetoma (especially for E. jeanselmei), localized cutaneous infections, subcutaneous cysts, endocarditis and cerebral and disseminated infections. Phaeohyphomycosis caused by Exophiala species has been reported in both normal and immunosuppressed patients.
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.
