Human infections by black yeasts of genus Exophiala

Clinical and laboratory aspects of the infections caused by Exophiala species are reviewed with regard to its epidemiology, diagnosis and treatment. Exophiala is a genus of dematiaceous hyphomycetes whose taxonomy and nomenclature undergo constant revision. Exophiala species are widely distributed in nature, and they are uncommon human pathogens. In recent years it appears to have increased its frequency as a cause of human infections, mainly in immunocompromised patients. They have been associated with phaeohyphomycosis, chromoblastomycosis, eumycotic mycetoma and disseminated infection. The procedures recommended for diagnosis consist of detection of fungal elements in tissue and growth of the organism in culture. Identification is mostly based upon microscopic observation of morphological characteristics and conidiogenesis, combined with the evaluation of physiological tests and nitrate and carbohydrate assimilations. Antifungal agents such as amphotericin B, itraconazole and voriconazole showed in vitro activity to most of the Exophiala species of clinical interest. The therapeutic recommendations are mainly deduced from the observation of single cases.