Molecular epidemiology of Candida species isolated from clinical specimens and evaluation of their antifungal susceptibility testing to ketoconazole and nystatin with a review of studies

Abstract

Introduction: Candidiasis is a fungal infection caused by Candida yeasts in immunocompromised patients. This study aimed to assess antifungal susceptibility of clinical isolates of Candida species to ketoconazole and nystatin by broth microdilution. Material & Methods: In this descriptive-analytical study, 377 clinical isolates of Candida species were collected from different regions of Iran. The species were identified using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method. The antifungal susceptibility testing of clinical isolates of Candida species to ketoconazole and nystatin was performed using broth microdilution according to standard protocol CLSI (M27-A3 and M27-S4). The standard strain of Candida parapsilosis was used as the quality of control. The minimum inhibitory of concentrations was determined after 24h at 37 ºC. Results: Based on molecular identification, Candida albicans 266 (70.7%), C. krusei 64 (17%), C. parapsilosis 40 (10.7%), and C. tropicalis 6 (1.6%) were identified. The MIC90 and MIC50 values of ketoconazole and nystatin for all isolates were 0.063 µg/ml, 0.031 µg/ml, 2 µg/ml, and 4 µg/ml, respectively. Discussion & Conclusion: As evidenced by the results of this study, antifungal susceptibility testing along with the identification of fungi at the species level would certainly be very useful in selecting primary antifungal agents for treatment, especially in invasive fungal infections. According to our findings, ketoconazole was much more effective on Candida spp. than nystatin.

Keywords

• antifungal susceptibility testing
• candida
• molecular identification