Abstract
Recurrent vulvovaginal candidiasis (RVVC) is a common condition that affects women of reproductive age. The etiology of RVVC remains largely unknown, but it is believed to be associated with changes in vaginal microbiota composition. This study investigates the vaginal microbiota in 57 women with RVVC and 38 healthy controls. Bacterial DNA was analyzed using high-throughput 16S rRNA gene sequencing, and Candida and Saccharomyces species were determined by PCR. RVVC cases had a higher prevalence of Nakaseomyses glabratus (former Candida glabrata) compared to controls. Alpha diversity metrics were similar between groups, but beta diversity analysis revealed significant differences in vaginal microbiota composition. The Firmicutes abundance was altered in RVVC cases, with genus Bifidobacterium and phylum Actinobacteriota being more abundant than in the controls. At the genus level, Lactobacillus dominated controls using antibiotics, while Bifidobacterium was higher in cases with no antibiotic intake. Our study provides evidence that Nakaseomyses glabratus (former Candida glabrata) is a significant pathogen in RVVC, while Candida albicans was more prevalent in healthy women. The vaginal microbiota composition differs significantly between the two groups, with distinct patterns of bacterial abundance and changes in Firmicutes abundance.