Comparison of the Sensititre YeastOne colorimetric microdilution panel and the NCCLS broth microdilution method for antifungal susceptibility testing against Candida species.

We evaluated the commercially prepared Sensititre YeastOne colorimetric antifungal panel to determine the susceptibility of 170 Candida spp isolates to amphotericin B, fluconazole, itraconazole, and flucytosine. The NCCLS reference microdilution method (M27-A document) was used as reference method. The YeastOne panel was performed according to the manufacturer's instructions. For the colorimetric method, MICs were determined at 24 h of incubation. MICs for the NCCLS reference method were read at 48 h of incubation. The overall agreement within +/-2 dilutions by both methods was calculated against the four antifungal agents. This agreement was 92.9, 68.2, 77.6 and 80% for amphotericin B, fluconazole, itraconazole, and flucytosine, respectively. Thirteen isolates (7.6%) showed very major discrepancies for fluconazole and 12 (7%) for itraconazole. We found that the reading of MIC with the YeastOne panel was somewhat easier than the reading of reference MIC, although the determination of endpoint was sometimes difficult, especially for azoles, because the trailing effect appeared in a high percentage of isolates.