Molecular Sequencing and Phylogenetic Analysis of Malassezia pachydermatis Isolates from Dogs and Cats

Niaee Barmachi, Nima; Bayat, Mansour; Sohrabi Haghdoost, Nakisa; Ghorbaniyekta, Batool; Eini Farahani, Leila

doi:10.22092/ari.2026.372093.4031

Molecular Sequencing and Phylogenetic Analysis of Malassezia pachydermatis Isolates from Dogs and Cats

Articles in Press

Document Type : Original Articles

Authors

¹ Department of Veterinary Pathobiology, SR.C., Islamic Azad University, Tehran, Iran

² Department of Physiology, Faculty of Medicine, TeMS.C., Islamic Azad University, Tehran, Iran

³ Department of Veterinary Basic Sciences, SR.C., Islamic Azad University, Tehran, Iran

10.22092/ari.2026.372093.4031

Abstract

Abstract
Introduction: Malassezia pachydermatis is a lipophilic yeast that is part of the normal skin microbiota of dogs and cats but can act as an opportunistic pathogen associated with dermatitis and otitis externa. Molecular characterization is essential for understanding its genetic diversity and epidemiology. This study aimed to perform ITS-1-based sequencing and phylogenetic analysis of M. pachydermatis isolates from companion animals.
Materials and Methods: A total of 300 clinical samples were collected from dogs and cats with dermatological lesions or otitis externa in northern Iran. Isolates were identified by culture on modified Dixon agar and ITS-1 PCR. Ten representative isolates were sequenced using the Sanger method. Sequence similarity was analyzed using BLAST, and phylogenetic relationships were inferred using the Neighbour-Joining method with the Kimura two-parameter model and 1000 bootstrap replications.
Results: Eighty isolates were identified as Malassezia spp., including 87.5% M. pachydermatis and 12.5% M. nana. All sequenced isolates showed ≥98% similarity with reference strains. Phylogenetic analysis revealed clustering mainly within genotype B. No host-specific clustering was observed between canine and feline isolates. Most isolates showed identical or closely related haplotypes, with high bootstrap support (>70%).
Conclusion:The results indicate high genetic homogeneity among M. pachydermatis isolates. ITS-1 sequencing is a reliable method for molecular identification and phylogenetic analysis. The lack of host-specific clustering suggests a shared population structure between canine and feline isolates.

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