MULTISITE REPRODUCIBILITY OF COLORIMETRIC BROTH MICRODILUTION METHOD FOR ANTIFUNGAL SUSCEPTIBILITY TESTING OF YEAST ISOLATES

MICs of fluconazole and amphotericin B were determined independently f or 100 coded yeast isolates by each of six laboratories to determine r eproducibility of results by using a colorimetric oxidation-reduction- based broth microdilution test. In addition, each site tested five qua lity control isolates on at least four different occasions during the study. Results agreed within a three-dilution range (mode +/- 1 log(2) dilution) for 96.2% of fluconazole tests and 92.7% of amphotericin B tests. Agreement among tests with the quality control isolates was 99. 4% with fluconazole and 98.6% with amphotericin B. These results indic ate that the colorimetric microdilution method is reproducible among l aboratories.