Comparative evaluation of Fungitest, Neosensitabs and broth microdilution method for yeasts susceptibility testing

The need of a simple and reliable method for routine yeasts susceptibility testing led us to evaluate two commercially available methods. We investigated the in vitro susceptibility of 67 clinical isolates (26 C. albicans, 32 C. glabrata, 4 C. krusei, 2 C. tropicalis, 2 C. kefyr and 1 S. cerevisiae) to 6 drugs flucytosine (FC), amphotericin B (A), fluconazole (FZ), itraconazole (IT), kétoconazole (K), miconazole (M), comparing two methods Fungitest (Sanofi Pasteur) and Neosensitabs (Rosco). A broth microdilution adaptation from the NCCLS-M27A procedure was used as reference method. Fungitests consist of individually packed 16 wells microplates containing 6 drugs at two critical concentrations in buffered medium. Reading was performed after 24 and 48h incubation. Neosensitabs is an agar diffusion method on Shadomy agar using antifungals tablets. Reading was performed after 24h. For all strains Neosensitabs was in concordance with NCCLS M27-A for FC (94%), A (98%), FZ (55%) I (53%) with p<0.05. Fungitest correlated with NCCLS method for all antifungals after 24 and 48h incubation time (p<0.05) with respectively 95/95% for FC, 100/100% for A, 80/76% for FZ, 81/55% for I and 93/75% for K, and 88/81 for M. Candida glabrata gave the poorest result with Neosensitabs with 28% concordance for FZand 39% for I; therefore the method can't be recommended for this species. Fungitest concordance observed was 55% for I after 48h. Our results suggest that Fungitest is appropriate for routine yeast susceptibility testing. However itraconazole testing has to be improved with this method.