Determination of the antimycotic profiles of Malassezia pachydermatis isolated from dogs with Otitis eksterna

This study was conducted to determine the in vitro susceptibility profiles of yeast isolates obtained from dogs diagnosed with otitis externa against various antifungal agents. Ear swab samples were collected from 80 dogs clinically diagnosed with otitis externa and cultured. Antifungal susceptibility testing was performed using a modified broth microdilution method based on EUCAST standards. Ten antifungal agents were tested: Amphotericin B, Fluconazole, Flucytosine, Griseofulvin, Itraconazole, Ketoconazole, Miconazole, Nystatin, Terbinafine, and Voriconazole. Minimum inhibitory concentration (MIC) values were determined for each antifungal agent. Additionally, the biofilm-forming abilities of the isolates were assessed using the tube adherence test and the microtiter plate method. As a result, 50 yeast isolates were obtained. Identification revealed that all isolates belonged to Malassezia pachydermatis. According to the MIC results, all isolates showed high susceptibility to the tested antifungal agents except for flucytosine and griseofulvin. In the biofilm assays, none of the isolates demonstrated biofilm formation. Based on these findings, it was concluded that antifungal susceptibility testing could be an important criterion in guiding effective treatment protocols for yeast-associated otitis externa cases.