A Ketoconazole Susceptibility Test for <i>Malassezia pachydermatis</i> Using Modified Leeming–Notman Agar

Abstract

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

• disk diffusion
• minimal inhibitory concentration
• <i>Malassezia pachydermatis</i>
• ketoconazole