Gentamycin inhibits the growth of Malassezia pachydermatis in culture.

BACKGROUND Malassezia pachydermatis is a yeast of importance in both veterinary and human medicine. AIMS To know if M. pachydermatis grow on mycological media with high concentrations of gentamycin. METHODS Twenty M. pachydermatis strains were streaked on Sabouraud Dextrose Agar plates with different concentrations of gentamycin. RESULTS All isolates were inhibited when high concentrations of gentamycin were added. CONCLUSIONS The use of plates with high concentrations of gentamycin can lead to some important misdiagnoses: firstly, false-negative cultures, and secondly, an erroneous classification of M. pachydermatis as a lipid-dependent species. Moreover, all of this could be useful in two therapeutic fields: i) in animals, topical gentamycin could be an efficacious treatment for a disease such as external otitis in dogs; ii) in humans, we hypothesize that gentamycin could be regarded as a possible therapy ("antibiotic-lock") for catheter-associated Malassezia spp. infections.