Abstract
The vaginal microbiome (VM), a complex and dynamic microbial ecosystem, is now recognized as a central determinant of female reproductive and gynecologic health. Under homeostatic conditions, a Lactobacillus-dominant ecosystem maintains vaginal acidity, provides colonization resistance, and modulates mucosal immunity. Conversely, vaginal dysbiosis-characterized by Lactobacillus depletion and anaerobic or aerobic overgrowth-is associated with infectious vaginitis, increased susceptibility to sexually transmitted infections, and non-infectious conditions such as genitourinary syndrome of menopause. This review provides an integrated overview of the composition, functional characteristics, and host interactions of the VM across health and disease. We highlight major mechanisms by which microbial dysbiosis contributes to disease pathogenesis, including biofilm formation, altered microbial metabolism, and immune dysregulation. In addition, we discuss the translational potential of the VM as a source of diagnostic and prognostic biomarkers and as a target for emerging microbiome-dependent therapeutic strategies. Collectively, current evidence supports the view that vaginal dysbiosis is a heterogeneous and context-dependent state driven by distinct pathogen- and host-related mechanisms, underscoring the importance of prioritizing microbiome restoration rather than pathogen eradication alone.