Profiling of vaginal Candida isolates from South African women: Exploring potential alternative therapeutic strategies.

Abstract

Introduction: Candida albicans remains the leading cause of vulvovaginal candidiasis (VVC), posing a persistent threat to women’s reproductive health globally. Increasing resistance to azole antifungals, driven by strain diversity, biofilm formation, and molecular mechanisms such as ERG11 overexpression, has complicated treatment outcomes and contributed to recurrent infections. Despite extensive global research, there is limited data from South Africa regarding genotype distribution, resistance patterns, and the role of alternative therapeutics. Methods: A cross-sectional study was conducted using stored Candida isolates obtained from pregnant and non-pregnant women attending Victoria Mxenge Hospital in Durban, South Africa. Isolates were confirmed as C. albicans using germ-tube testing and molecular identification. Antifungal susceptibility was assessed via broth microdilution to determine fluconazole minimum inhibitory concentrations (MICs). ABC genotyping of the 25S ribosomal deoxyribonucleic acid (rDNA) region classified isolates into genotypes A, B, and C. Molecular analysis involved ribonucleic acid (RNA) extraction, complementary deoxyribonucleic acid (cDNA) synthesis, and droplet digital PCR (ddPCR) to quantify ERG11 expression. Phylogenetic analysis assessed genetic relationships. Additionally, nanoemulsions derived from Azadirachta indica, Moringa oleifera, and Ocimum tenuiflorum, along with Lactobacillus cell-free supernatants (CFS), were evaluated for antifungal and antibiofilm activity using MIC and microtiter plate (MTP) assays. Results: All 72 isolates were identified as C. albicans, with genotype A predominating (62.5%), followed by genotype B (26.4%) and genotype C (11.1%). Fluconazole resistance was observed in 13.9% of isolates, with MICs ranging from 8 μg/mL to >256 μg/mL. Resistance was strongly associated with genotypes A and C, while genotype B remained fully susceptible. Significant ERG11 overexpression (1.31-3.73-fold) was detected in most resistant isolates, although one isolate demonstrated resistance independent of ERG11 upregulation. Phylogenetic analysis revealed clustering of resistant strains. While fluconazole was ineffective against resistant biofilms, plant nanoemulsions at 1000 μM completely inhibited biofilm formation, and Lactobacillus CFS significantly reduced early biofilm development, though efficacy varied by strain. Conclusion: These findings highlight emerging resistance trends and support the potential of alternative therapeutics in managing drug-resistant and recurrent VVC (RVVC) in South Africa.