Determination of the effect of fluconazole against Candida albicans and Candida glabrata by using microbroth kinetic assay

Aim: To evaluate the antifungal activity of a model antifungal (fluconazole) against Candida albicans (ATCC 90028) and Candida glabrata (RSKK 04019) strains using a microbroth kinetic assay based on continuous monitoring of changes in the optical density of fungal growth. Recently, antifungal susceptibility testing has become more important because of the increasing incidence of both fungal infections and antifungal drug resistance. Materials and methods: The optical growth densities of C. albicans and C. glabrata in the presence of increasing concentrations of fluconazole were measured every 15 min for 24 h at 35 degrees C, using a multidetection microplate reader at 405 nm. The turbidimetric growth curves of these strains were obtained, and the minimal inhibitory concentration (MIC) values for fluconazole were determined with this kinetic assay. Furthermore, the conventional broth microdilution method was performed according to Clinical and Laboratory Standards Institute reference method M27-A2. Results: MIC90 values for fluconazole were determined as 0.31 mu g/mL for C. albicans and 16.32 mu g/mL for C. glabrata. Conclusion: Using kinetic procedures, the effects of antifungal drugs on target yeasts can be determined at any desired time-point of the incubation period.