The aim of this study was to establish a ketoconazole susceptibility test for Malassezia pachydermatis using modified Leeming⁻Notman agar (mLNA). The susceptibilities of 33 M. pachydermatis isolates obtained by modified CLSI M27-A3 method were compared with the results by disk diffusion method, which used different concentrations of ketoconazole on 6 mm diameter paper disks. Results showed that 93.9% (31/33) of the minimum inhibitory concentration (MIC) values obtained from both methods were similar (consistent with two methods within 2 dilutions). M. pachydermatis BCRC 21676 and Candida parapsilosis ATCC 22019 were used to verify the results obtained from the disk diffusion and modified CLSI M27-A3 tests, and they were found to be consistent. Therefore, the current study concludes that this new novel test-using different concentrations of reagents on cartridge disks to detect MIC values against ketoconazole-can be a cost-effective, time-efficient, and less technically demanding alternative to existing methods.
Keywords: Malassezia pachydermatis; disk diffusion; ketoconazole; minimal inhibitory concentration.