Evaluation of semisolid agar screening tests for determining fluconazole and amphotericin B susceptibilities of Candida strains by using three different media

The susceptibilities of 164 Candida isolates against fluconazole and amphotericin B were determined by semisolid agar screening tests and the microdilution method according to NCCLS M27-A standards. The semisolid agar screening tests were performed with three different media containing 0.5% agar and 2, 8, and 40 mug/ml of fluconazole or 0.5 and 2.0 mug/ml of amphotericin B. These media were MOPS buffered RPMI 1640, brain-heart infusion and 1/3 diluted Sabouraud dextrose agar. The results of both methods were interpreted as susceptible, dose dependent susceptible and resistant for fluconazole and susceptible and resistant for amphotericin B. The agreement rates of semisolid agar screening tests using RPMI 1640, brain-heart infusion and Sabouraud dextrose media with the reference microdilution method were found to be 71.4%, 51.2%, and 57.3% for fluconazole and 79.3%, 53.7%, and 56.7% for amphotericin B, respectively. Overall, we conclude that semisolid agar screening tests using RPMI 1640 can be used for determining the susceptibilities of Candida isolates against fluconazole and amphotericin B in clinical microbiology laboratories.