Cryptic Diversity of Malassezia pachydermatis from Healthy and Diseased Domestic Animals.

Malassezia pachydermatis is part of the normal cutaneous microbiota of wild and domestic carnivores. However, under certain conditions this yeast can overproliferate and cause several diseases in its host, mainly otitis and dermatitis in dogs. The aim of this study was to conduct a molecular characterization of M. pachydermatis isolates from healthy and diseased domestic animals, in order to assess the molecular diversity and phylogenetic relationship within this species. The large subunit (LSU) and the internal transcribed spacer (ITS) of ribosomal RNA, chitin synthase 2 (CHS2) and β-tubulin genes from sixteen strains isolated from dogs, cats, a goat, a pig and a horse were sequenced. A different number of types of sequences were identified for each target gene, including some types described for the first time. Five sequence types were characterized for the LSU, eleven for the ITS region, nine for CHS2 and eight for β-tubulin. A multilocus analysis was performed including the four genes, and the resulting phylogenetic tree revealed fifteen genotypes. Genotypes were distributed in two well-supported clades. One clade comprised strains isolated from different domestic animals and a strongly supported cluster constituted by strains isolated from cats. The second clade included strains isolated mainly from dogs and an outlier strain isolated from a horse. No apparent association could be observed between the health status of the animal hosts and concrete strains. The multilocus phylogenetic analysis is a useful tool to assess the intraspecific variation within this species and could help understand the ecology, epidemiology and speciation process of M. pachydermatis.