Antifungal Susceptibility Patterns of Phenotypic Variants of Mouth Isolates of Candida albicans

Objectives: Candida albicans, a common human yeast pathogen, can switch between several different phenotypes. Some of these phenomena are closely correlated with its pathogenicity and their antifungal susceptibilities. The present study aimed to determine the susceptibility to antifungal drugs of phenotypic variants of C. albicans isolated from oral cavity of healthy individuals. Methods: In the present study, 25 isolates of C. albicans from the mouth cavity of healthy individuals were inoculated on Phloxin B agar plates and incubated at 37°C for 5 days. Drug susceptibility testing of different phenotypes against 6 antifungal drugs (bifonazole, fluconazole, econazole, miconazole, terbinafine and amphotericin B) was performed by using micro broth dilution technique as described by CLSI. Results: In the present study, 6 different phenotypes of C. albicans, including fuzzy, stars, stippled, dark pink, white and pale pink colonies were identified. All phenotypes were sensitive to fluconazole. 16 out of 50 phenotypic variants of C. albicans were resistant to econazole, and 36 phenotypes were resistant to amphotericin B. Terbinafine and bifonazole were active at 8 μg/mL or lower concentrations while miconazole activity was observed at 1 μg/mL or more concentrations. Conclusion: Our results showed that all phenotypic variants of C. albicans are sensitive to fluconazole at ≤ 8 μg/mL whereas other antifungals have variable effects on phenotypic variants of C. albicans.

Phenotypic