Identification of atypical strains of Malassezia spp. from cattle and dog

Area of Science:

• Veterinary Mycology
• Microbiology
• Yeast Taxonomy

Background:

• Malassezia yeasts are typically lipophilic, except for Malassezia pachydermatis.
• The genus Malassezia plays a role in skin health and disease in animals.

Purpose of the Study:

• To investigate the occurrence and characteristics of Malassezia species in the external ear canal of cattle and dogs.
• To identify and characterize unusual lipid-dependent Malassezia isolates.

Main Methods:

• Culturing yeast from ear swabs of 964 cattle and 6 dogs.
• Testing isolates for lipid dependency using Tweens and Cremophor EL.
• Biochemical tests including esculin hydrolysis and catalase production.
• Partial large subunit rRNA gene sequencing for identification.

Main Results:

• Six lipid-dependent Malassezia isolates were recovered that did not match known species.
• Isolates grew on Tweens but not Cremophor EL as a sole lipid source.
• One isolate from a cow with otitis was identified as a lipid-dependent M. pachydermatis variant.
• One isolate from a dog was identified as an atypical Malassezia furfur variant.

Conclusions:

• The study identified novel lipid-dependent Malassezia variants in cattle and dogs.
• These findings highlight the potential for unrecognized Malassezia diversity and host-specific adaptations.
• Further research is needed to understand the clinical significance of these variants.