Elucidation of vaginal microbiota of women associated with bacterial vaginosis from Northern region of India

Bacterial vaginosis (BV) is a prevalent vaginal dysbiosis that disproportionately affects women of reproductive age and is associated with adverse reproductive and sexual health outcomes. Despite its substantial global burden, diagnosis of BV remains challenging due to its polymicrobial nature, ecological complexity and lack of definitive biomarkers, contributing to recurrence rates exceeding 50%. Conventional diagnostic methods are intrinsically subjective and limited in capturing full taxonomic and ecological landscape of the vaginal microbiota. In this study, we aimed to comprehensively characterize the vaginal microbiota across BV-negative, BV-intermediate and BV-positive states in women from Northern India, using high-throughput 16S rRNA gene sequencing. We found that BV-positive women exhibited significantly greater microbial richness and diversity, marked by a shift from Lactobacillus-dominated communities to polymicrobial consortia enriched with Gardnerella, Sneathia, Prevotella, Atopobium, Megaspharea and Dialister. In contrast, BV-negative profiles were dominated by Lactobacillus, reflecting a stable eubiotic state, while BV-intermediate samples showed a transitional microbiota state. Differential abundance analysis revealed significant enrichment of BV-associated genera in dysbiotic states. Random Forest modeling identified Lactobacillus, Gardnerella, Atopobium, Veillonellaceae, Sneathia, Prevotella as the top predictors of BV status. Functional predictions indicated enrichment of secondary metabolite biosynthesis and pathogen-associated pathways in BV-positive samples, suggesting a metabolically altered and dysbiotic vaginal environment.