A Study for Testing the Antifungal Susceptibility of Yeast by the Japanese Society for Medical Mycology (JSMM) Method

-The Proposal of the Modified JSMM Method 2009-

Abstract

The Japanese Society for Medical Mycology (JSMM) method used for testing the antifungal susceptibility of yeast, the MIC end point for azole antifungal agents, is currently set at IC₈₀. It was recently shown, however that there is an inconsistency in the MIC value between the JSMM method and the CLSI M27-A2 (CLSI) method, in which the end- point was to read as IC₅₀. To resolve this discrepancy and reassess the JSMM method, the MIC for three azoles, fluconazole, itraconazole and voriconazole were compared to 5 strains of each of the following Candida species: C. albicans, C. glabrata, C. tropicalis, C. parapsilosis and C. krusei, for a total of 25 comparisons, using the JSMM method, a modified JSMM method, and the CLSI method. The results showed that when the MIC end- point criterion of the JSMM method was changed from IC₈₀ to IC₅₀ (the modified JSMM method) , the MIC value was consistent and compatible with the CLSI method. Finally, it should be emphasized that the JSMM method, using a spectrophotometer for MIC measurement, was superior in both stability and reproducibility, as compared to the CLSI method in which growth was assessed by visual observation.