Bacterial Vaginosis vs. Aerobic Vaginitis: An Unresolved Conundrum?

Bacterial vaginosis (BV) and aerobic vaginitis (AV) are usually described as distinct forms of vaginal dysbiosis. BV is characterized by depletion of lactobacilli, overgrowth of anaerobic microorganisms, and biofilm formation, whereas AV is associated with inflammatory changes, epithelial disruption, and predominance of aerobic bacteria. Over the past two decades, this distinction has profoundly influenced the understanding, diagnosis, and management of vaginal disorders. Despite their apparent differences, the relationship between BV and AV remains incompletely understood. Growing evidence indicates that many women exhibit microbiological and microscopic patterns that cannot be readily classified within existing diagnostic frameworks. Intermediate Nugent scores, mixed vaginitis, transitional ecological states, post-treatment microbiota reconstitution, physiological hypoestrogenic conditions, and uncommon inflammatory patterns all challenge the traditional view of BV and AV as strictly separate entities. This narrative review examines the historical evolution of BV and AV concepts, compares their microbiological, immunological, and epithelial characteristics, and evaluates the diagnostic paradigms currently used to identify vaginal dysbiosis. The strengths and limitations of clinical and diagnostic approaches are discussed together with the extent to which contemporary international guidelines reflect current biological knowledge. Particular emphasis is placed on intermediate, mixed, and overlapping states that blur the boundaries between established diagnostic categories. The available evidence supports the clinical usefulness of distinguishing BV and AV as separate clinicopathological entities. However, it also indicates that vaginal ecosystem disturbances frequently extend beyond rigid dichotomous classifications. Current diagnostic categories remain valuable tools for clinical practice, yet they may only partially capture the complexity and dynamic nature of vaginal dysbiosis. Understanding how microbial communities, host responses, epithelial integrity, and physiological factors interact remains a major challenge for future research and clinical interpretation.