Comparative evaluation of standard dilution method and commercial kit for frozen plate antifungal susceptibility testing of yeasts using 200 clinical isolates

Abstract

A comparative evaluation of standard microdilution methods and a commercial kit for frozen plate antifungal susceptibility testing of yeasts was performed using amphotericin B, flucytosine, fluconazole, miconazole, and itraconazole on 200 yeast isolates. The isolates included 100 strains of Candida albicans, eight of C. tropicalis, twelve of C. parapsilosis, eight of C. glabrata, five of Cryptococcus neoformans, thirteen of Trichosporon asahii, and 54 other strains of seven other species of ascomycotic yeasts. Microdilution testing was performed according to the standard method for antifungal susceptibility testing published by the Japanese Society for Medical Mycology (JSMM), which are a modification of the method developed by the National Committee for Clinical Laboratory Standards (NCCLS) M27-P. The commercial kit was prepared according to the manufacturer's instructions. The degree of agreement within ±1 dilution for 200 clinical isolates against five antifungal agents was excellent with values for amphotericin B, flucytosine, fluconazole, miconazole, and itraconazole of 100%, 99.0%, 97.5%, 97.0%, and 97.0%, respectively. Overall, the frozen plate antifungal susceptibility testing kit provided convenient and reproducible results comparable to those obtained with the JSMM standard method.