Bacterial vaginosis

The normal vaginal ecosystem is composed predominantly of Lactobacillus species (producers of hydrogen peroxide), with or without Gardnerella vaginalis. In bacterial vaginosis (BV), the most common of the three vaginitides, the quantity of lactobacilli is severely reduced and anaerobic bacteria (e.g., Prevotella bivia, Mobiluncus spp., Peptostreptococcus spp.) predominate along with the facultative organism, G. vaginalis. The bacterial load also increases from 107 to 1010 c.f.u./ml of vaginal fluid. Clinical diagnosis of BV requires the presence of three of the following four characteristics: (i) pH > 4.5; (ii) clue cells; (iii) homogeneous discharge; (iv) fishy odor. Laboratory diagnosis can be made by Gram stain or detection of G. vaginalis rRNA (Affirm, Becton-Dickinson) plus pH > 4.5 and fishy odor. Some studies have shown a higher relative risk of acquiring BV in women with more male sexual partners; however, treatment of male partners has not shown decreased acquisition in the female. BV is very common among lesbian women. Oral sex appears to be a risk factor for heterosexual and lesbian acquisition. Obstetrical sequelae of BV include preterm birth, low birth weight, chorioamnionitis, and amniotic fluid infection. Non-obstetrical infections include postpartum endometritis, pelvic inflammatory disease, cuff cellulitis, neonatal scalp abscess, non-puerperal breast abscess and cervicitis. BV increases the risk of acquiring HIV infection. Based on current data, the pathogenesis involves lysis of lactobacilli by bacteriophage with reduction of protective hydrogen peroxide that allows overgrowth by Prevotella, Mobiluncus, and Gardnerella. Signs and symptoms of BV appear to be attributable to products of these organisms.