[Yeasts of the genus Malassezia: taxonomic classification and significance in (veterinary and) clinical medicine]

Abstract

The historical development of the taxonomic classification of Malassezia yeasts until today yielded the description of seven different species based upon molecularbiological, morphological and biochemical parameters (M. furfur, M. pachydermatis, M. sympodialis, M. globosa, M. obtusa, M. restricta, M. slooffiae). Tests like Cremophor EL assimilation, esculin degradation, catalase test, pigment production and determination of polidocanol sensitivity appear to be suitable procedures for routine identification of the different species. Their colonization of clinically healthy humans (in particular M. sympodialis, M. globosa, M. obtusa) and animals (M. pachydermatis) skin renders interpretation difficulties, when isolating Malassezia spp. from clinical specimens. Out of the seven species, in man the clinical significance of M. furfur for pityriasis versicolor and systemic infections appears to be accepted largely. In dogs and cats M. pachydermatis has been regarded as cause of otitis externa and seborrhoeic dermatitis. But, due to geno- and phenotypic variabilities described for M. pachydermatis field isolates further investigations concerning the taxonomic uniformity of the species are necessary.