Commercial tests for in vitro antifungal susceptibility testing of Candida species compared to standard (NCCLS) broth microdilution

摘要

  It is of value to evaluate the commercial susceptibility methods as possible alternatives to standard one for routine fungal susceptibility testing. So we aimed to compare the NCCLS microdilution method with each of commercial Etest and candifast kit. A total of 30 Candida isolates were included and species identification was confirmed by morphological appearance on Sabouraud's dextrose agar (SDA), Gram stain, and candifast kit. The in vitro antifungal susceptibility testing of amphotericin B (AMB) and fluconazole (FCZ) were performed by 3 methods (standard broth microdilution, Etest and candifast) on the tested Candida species. The overall percentage of agreement of Etest with standard method was 90% for each of AMB and FCZ. For AMB the agreement of Etest with standard broth method was 100% in tested species exceptCandida glabrata (85.7%) and Candida parapsilosis (66.6%), while the percentage of agreement of candifast was100% in all species except C. glabrata (85.7%).  For fluconazole the percentage of agreement of Etest, with the standard method, was 100% for each of C. glabrata and Candida tropicalis and was 92.8, 66.6% for Candida albicansand Candida parapsilosis respectively. The percentage of agreement of candifast method was 100% in all species except C. albicans, C. glabrata which was 92.8 and 85.7% respectively. Etest method is an alternative but cannot be considered as a substitute for the NCCLS reference method. The antifungal susceptibility method not greatly influenced by the type of tested antifungal agent.