Antifungal Susceptibility of Candida albicans Isolates at a Tertiary Care Hospital in Bulgaria

Background: The precise identification of yeasts and their antifungal sensitivity is a key factor in the choice of a suitable drug for treatment and prevention of fungal infections. Objectives: The aim of the present study was to determine in vitro susceptibility of clinical Candida albicans isolates to nine antifungal agents. Methods: A total of 61 C. albicans isolates were tested. Antifungal susceptibility was evaluated by determination of minimum inhibitory concentrations (MIC). Results: Fifty C. albicans isolates were susceptible to nine antifungal agents. The remaining 11 yeasts were resistant to one or more antifungals. All C. albicans were susceptible to amphotericin B with MICs 0.25 to 1 μg/mL and exhibited sensitivity to 5-fluorocytosine with MIC90 of 0.125 μg/mL. The MIC50 and MIC90 of fluconazole were 0.5 and 32 μg/mL, whereas the MIC50 and MIC90 of voriconazole were considerably lower - 0.0078 and 2 μg/mL. The isolates showed susceptibility to echinocandins with MIC90 of micafungin, anidulafungin and caspofungin of 0.015, 0.031, and 0.125 μg/mL, respectively. Of particular interest was detection of seven C. albicans isolates, which expressed a high-level resistance to all azoles and one of them was also resistant to echinocandins. Conclusions: In conclusion, detection of resistance in C. albicans, which is a species typically susceptible to antifungals, is of great importance for clinical practice.