Phaeohyphomycosis

Infections caused by a group of melanised or dematiaceous fungi in vertebrates and invertebrates are described as phaeohyphomycosis. Diverse groups of melanised yeast and filamentous fungal species are identified as causative agents of phaeohyphomycosis. Identification of melanised fungi by phenotypic methods needs taxonomical and mycological expertise. As these agents sporulate poorly in culture media, phenotypical identification is unreliable. Hence, the use of molecular methods is essential for accurate identification. Phaeohyphomycotic infections in humans and animals may present with similar clinical manifestations, such as allergic rhinitis, keratitis, and subcutaneous and cerebral infections. The pathogenesis of phaeohyphomycosis is attributed to virulence factors such as melanin, carotenoids, and chitin synthases. Furthermore, innate and cell-mediated immune responses, along with host receptors, play a role in the pathogenesis of the disease. The genomic and transcriptomic studies identified the genes responsible for cell structure, virulence factors, and drug resistance mechanisms. Most melanised fungi are resistant to antifungal drugs. Hence, the antifungal susceptibility profile of the medically important species needs to be evaluated to design an appropriate treatment regime.