Improved method of determining the susceptibility of Candida albicans to fluconazole

The MICs of fluconazole for four reference strains of Candida albicans were determined in one laboratory by the macrobroth dilution method recommended by the National Committee for Clinical Laboratory Standards (NCCLS) and by a modified version of the method which incorporated microbroth dilution, RPMI 1640 medium supplemented with glucose and the reading of MIC endpoints by spectrophotometry. The results obtained by the two methods were within one two-fold dilution. In addition, the susceptibilities of 58 clinical isolates of C. albicans to fluconazole were determined in two laboratories by the modified NCCLS method. Close interlaboratory agreement was observed, 98.2% of MICs varying by no more than one two-fold dilution.