ANTIFUNGAL SUSCEPTIBILITY TESTING USING THE E-TEST - COMPARISON WITH THE BROTH MACRODILUTION TECHNIQUE

The National Committee for Clinical Laboratory Standards reference bro th macrodilution method for antifungal susceptibility testing was comp ared with the E test by testing 86 clinical isolates of Candida spp. a nd Cryptococcus neoformans. The MIC agreement rates for the two method s for Candida spp. were 73-89% within +/- 1 doubling dilution and 87-1 00% within +/- 2 dilutions. For C. neoformans, agreement within +/- 1 dilution was > 70% for all the agents tested except fluconazole for wh ich agreement was 35%. Our data support the further evaluation of the E test as an alternative method for antifungal susceptibility testing. However, E test MICs of fluconazole for C. neoformans, particularly C . neoformans var. gattii should be interpreted with caution, as falsel y elevated MICs may occur.