The Restoration of the Vaginal Microbiota After Treatment for Bacterial Vaginosis with Metronidazole or Probiotics

Whether or not treatment with antibiotics or probiotics for bacterial vaginosis (BV) is associated with a change in the diversity of vaginal microbiota in women was investigated. One hundred fifteen women, consisting of 30 healthy subjects, 30 BV-positive control subjects, 30 subjects with BV treated with a 7-day metronidazole regimen, and 25 subjects with BV treated with a 10-day probiotics regimen, were analyzed to determine the efficacy and disparity of diversity and richness of vaginal microbiota using 454 pyrosequencing. Follow-up visits at days 5 and 30 showed a greater BV cure rate in the probiotics-treated subjects (88.0 and 96 %, respectively) compared to the metronidazole-treated subjects (83.3 and 70 %, respectively [p = 0.625 at day 5 and p = 0.013 at day 30]). Treatment with metronidazole reduced the taxa diversity and eradicated most of the BV-associated phylotypes, while probiotics only suppressed the overgrowth and re-established vaginal homeostasis gradually and steadily. Despite significant interindividual variation, the microbiota of the actively treated groups or participants constituted a unique profile. Along with the decrease in pathogenic bacteria, such as Gardnerella, Atopobium, Prevotella, Megasphaera, Coriobacteriaceae, Lachnospiraceae, Mycoplasma, and Sneathia, a Lactobacillus-dominated vaginal microbiota was recovered. Acting as vaginal sentinels and biomarkers, the relative abundance of Lactobacillus and pathogenic bacteria determined the consistency of the BV clinical and microbiologic cure rates, as well as recurrent BV. Both 7-day intravaginal metronidazole and 10-day intravaginal probiotics have good efficacy against BV, while probiotics maintained normal vaginal microbiota longer due to effective and steady vaginal microbiota restoration, which provide new insights into BV treatment.