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 micological 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. Morever, 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. (C) 2009 Revista Iberoamericana de Micologia. Published by Elsevier Espana, S.L. All rights reserved