Fonsecaea pedrosoi/monophora complex

Morphologically the genus Fonsecaea is defined by the presence of indistinct melanised conidiophores with blunt, scattered denticles bearing conidia singly or in short chains that eventually become branched.   de Hoog et al. (2004) revised the genus on the basis of ribosomal DNA internal transcribed spacer (ITS) sequence data recognising two species; F. pedrosoi and F. monophora.   The previously described species F. compacta was found to be a morphological variant of F. pedrosoi. Morphological F. pedrosoi and F. monophora are very similar and can best be distinguished by genetic analysis.   F. monophora on average has slightly longer conidial chains and slightly shorter denticles than F. pedrosoi.   All strains grow at 37C but not at 40C. Both species are recognised etiologic agents of chromoblastomycosis. RG-2 organism.

Colonies are slow growing, flat to heaped and folded, suede-like to downy, olivaceous to black with black reverse. Conidiogenous cells pale olivaceous, arranged in loosely branched systems, with prominent denticles. Conidia pale olivaceous, clavate to ellipsoidal, in short chains, subhyaline, smooth and thin-walled, 3.5-5 x 1.5-2 µm.

Conidiophores and conidia of Fonsecaea.

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

Clinical significance:

The genus contains two species, Fonsecaea pedrosoi and Fonsecaea monophora which are recognized etiologic agents of chromoblastomycosis.  Both species are soil fungi and F. pedrosoi is also associated with forest litter decomposition.

Mycosis: Chromoblastomycosis

Further reading:

McGinnis, M.R. 1980. Laboratory handbook of medical mycology. Academic Press, London, UK.

Rippon, J.W. 1988. Medical Mycology. 3rd Edition. W.B. Saunders Co., Philadelphia, USA