Recent progress in understanding the epidemiology of bacterial vaginosis.

PURPOSE OF REVIEW: Bacterial vaginosis epidemiology has been transformed by new theoretical insights and methodologies, such as molecular sequencing. We summarize the progress made in these domains. RECENT FINDINGS: The vaginal microbiome can be classified in five to eight clusters. Bacterial vaginosis-type clusters typically constitute one of these clusters, but in higher risk women, it can constitute up to three clusters. The vaginal microbiomes may be fairly stable or be subject to rapid changes in their constitutive makeup. Bacterial vaginosis does not appear to be a single entity. Certain bacterial communities are associated with particular symptoms of bacterial vaginosis that are paired with unique adverse outcomes. Biofilm-producing Gardnerella vaginalis are likely to play an important role in initiating the structured polymicrobial biofilm that is a hallmark of bacterial vaginosis. SUMMARY: Longitudinal studies currently underway should help elucidate how to best define bacterial vaginosis and its subtypes. Risk factors and outcomes associated with particular bacterial vaginosis subtypes should also be further clarified through these studies.