Molecular analysis of Malassezia sympodialis-related strains from domestic animals.

Recently, several new lipid-dependent species belonging to the genus Malassezia have been described. Some of them, such as Malassezia dermatis, Malassezia nana, and the tentatively named "Malassezia equi," have similar phenotypes and are genetically close to Malassezia sympodialis Simmons et Gueho 1990. DNA characterization by D1/D2 26S rRNA gene and internal transcribed spacer (ITS)-5.8S rRNA gene sequencing analysis of lipid-dependent strains from different animal species close to M. sympodialis is described and illustrated. Phylogenetic analysis of both the D1/D2 regions of 26S rRNA gene and ITS-5.8S rRNA gene sequences showed four distinct clusters. Cluster I included isolates from different animal species (horse, pig, and lamb) and the type culture of M. sympodialis. Cluster II included isolates from horses grouping close to the "M. equi" AJ305330 sequence. Cluster III comprised isolates mainly from goats. Cluster IV contained isolates mainly from cats grouping together with the M. nana AB075224 sequence. This last cluster included isolates from healthy and external otitic ears. All of these strains had identical 26S rRNA gene and ITS regions. It is not clear whether the value of these genetic differences is for the definition of species or whether they only demonstrate genetic variation among strains from different origins within M. sympodialis, which are in the course of differentiation and probably adaptation to specific animal hosts.