Bacterial Vaginosis

Bacterial vaginosis is a polymicrobial vaginal dysbiosis, not infection caused by one pathogen. Hydrogen-peroxide- and lactic-acid-producing lactobacilli normally help maintain an acidic vaginal environment. In BV, protective organisms are displaced by a dense mixed anaerobic community. The resulting rise in pH supports production of volatile amines, which account for the characteristic fishy odour. Molecular sequencing adds an important layer to this clinical picture. Communities dominated by Lactobacillus crispatus are generally the most stable and health-associated. L. iners represents a less protective intermediate state; it may persist through treatment and transition toward dysbiosis. BV-associated communities commonly contain several organisms at once, including multiple Gardnerella variants, Fannyhessea vaginae—formerly Atopobium vaginae—Prevotella, other strict anaerobes, and Candidatus Lachnocurva vaginae, previously called BVAB1. Gardnerella is not a single uniform species. G. vaginalis, G. piotii, G. leopoldii and G. swidsinskii are formally described, and several Gardnerella variants may coexist in one vaginal community. This is why a positive result for one organism does not, by itself, establish BV. The organisms also form an adherent polymicrobial biofilm on vaginal epithelium. Antimicrobials can suppress that community without fully...