Fungi of the genus Malassezia as opportunists of humans and animals

Abstract

Yeasts from the genus Malassezia are common commensals and pathogens found in humans and animals, and are responsible for tinea cases. Due to their specific cell structure, they may be resistant to environmental stresses and difficult to eliminate by the host’s immune system. In spite of several virulence factors, the pathogenicity of Malassezia spp. and their interactions with hosts still arouse great interest. Genomes of particular isolates, representing the majority of species from the Malassezia genus, have been sequenced in recent years. Moreover, reconstruction of the phylogeny, by the usage of ITS and IGS sequences, has been attempted as well. Biochemical analyzes led to a better understanding of those fungi’s ecology and virulence. Lipid and protein profiling, the assessment of phospholipases and extracellular enzymes activities, brought new insight into the genesis and courses of diverse illnesses, including pityriasis versicolor, seborrheic dermatitis, atopic dermatitis, Malassezia folliculitis, psoriasis and systemic fungemia. Special attention should be paid to Malassezia pachydermatis, which is a potential model of zoophilic species with an increasing frequency of tinea cases caused in humans. Furthermore, in vitro experiments suggest its possible drug resistance. The members of Malassezia genus are a serious medical and therapeutic challenge. Because of difficulties in the assessment of their virulence, high genetic and biochemical diversity and, finally, complicated evolutionary traits, they require further research. Genomic and proteomic analyses, supported with biochemical profiling and epidemiological data, will contribute to a better understanding of the biology of the yeasts, especially the issue of opportunism among fungi.