Evaluating the Sensitivity of Candida Albicans Isolates from Oral Candidiasis of AIDS Patients to Fluconazole by Microdilution Broth and Disk Diffusion Methods

Candida albicans is a pathogenic yeast that causes oral, vaginal and systemic infections. Oral candidiasis is treated with antifungal agents, particularly triazoles such as fluconazole. However, the overuse of fluconazole has resulted in the emergence of azole-resistant strains of Candida. This study tried to evaluate the sensitivity to fluconazole in strains of C. albicans clinical isolates from oral candidiasis of AIDS patients by broth microdilution and disk diffusion methods. The study included 66 C. albicans isolated from oral candidiasis of AIDS patients. C. albicans ATCC10231 was used as sensitive control and C. albicans ATCC76615 as resistant control. The minimum inhibitory concentrations (MICs) of fluconazole for all isolates were determined by broth microdilution assays for yeasts according to the clinical and laboratory standards institute (CLSI) guidelines. The MICs were evaluated after 48h of incubation at 35°C. The disk diffusion test was performed according to the procedure outlined in CLSI M44-S2 document. Mueller-Hinton agar supplemented with 2% glucose and 0.5 μg/ml of methylene blue was used and the results were read after 24h incubation at 35°C. Significant differences were not observed between broth microdilution and disk diffusion methods for evaluating the sensitivity of isolates to fluconazole. However, while broth microdilution is a difficult, time consuming technique, disk diffusion test is a quick and simple method for determining the sensitivity of yeasts to fluconazole.