Antifungal susceptibility and biofilm production of Candida species- causative agents of female genital tract infections.

Background: Recurrent vulvovaginal candidosis (RVVC) is a chronic infection affecting 8-10% of women worldwide. Biofilm production of the infecting species and reduced sensitivity to antimycotics could contribute to the recurrence of this infection. This study aimed to examine the biofilm production ability and antifungal susceptibility of genital yeast isolates to determine their virulence potential.

Methods: Matrix-assisted laser desorption in ionization-time of flight mass spectrometry (MALDI-TOF MS) was used to identify 300 Candida species. Using crystal violet method, strains were categorized into non-producers, weak, moderate, and strong biofilm producers (BFP). Antifungal susceptibility testing was performed using commercial Integral System YEASTS Plus test (ISYPT) and broth microdilution method (BMM).

Results: MALDI-TOF MS identified 150 Candida albicans, 124 non-albicans Candida (NAC), and 26 Saccharomyces cerevisiae strains. Within 138 (46.0%) BFP, 23 (16.7%) were strong, 44 (31.9%) moderate, and 71 (51.4%) weak. BMM was done for 43 BFP selected isolates with nystatin MIC ˃1.25 μl, fluconazole MIC ˃64 μl, and clotrimazole MIC ˃1.0 μl determined by ISYPT. Compared to all examined isolates, BMM confirmed that: i) C. albicans and NAC BFP showed low sensitivity to fluconazole (12% and 4%, respectively); ii) all BFP showed low sensitivity to nystatin (12.7% C. albicans, 14.5% NAC, and 23.1% S. cerevisiae); iii) clotrimazole in vitro was the most efficient regarding C. albicans and S. cerevisiae strains, but in 4.0% NAC BFP for this antimycotic higher MIC was established.

Conclusion: Novel antimycotics or possible combinations of antifungal agents and natural products could be a new treatment option for RVVC.