Temporal Variability of Human Vaginal Bacteria and Relationship with Bacterial Vaginosis

Background: Little is known about short-term bacterial fluctuations in the human vagina. This study used PCR to assess variability in concentrations of key vaginal bacteria in healthy women and the immediate response to antibiotic in women with bacterial vaginosis (BV). Methodology/Principal Findings: Twenty-two women assessed for BV using Amsel's criteria were evaluated daily for 7 14 days, then at 2, 3 and 4 weeks, using a panel of 11 bacterium-specific quantitative PCR assays. Participants with BV treated with 5 days of intravaginal metronidazole. Participants without BV had vaginal biotas dominated by whose levels fluctuated with menses. With onset of menstruation, quantities of Lactobacillus jensenii and crispatus decreased and were found to be inversely related to Gardnerella vaginalis concentrations (p<0.001). Women BV had a variety of fastidious bacteria whose concentrations dropped below detection thresholds 1-5 days after metronidazole. Recurrent BV was characterized by initial profound decreases of BV-associated bacteria after followed by subsequent increases at relapse. Conclusions/Significance: The microbiota of the human vagina can be highly dynamic. Healthy women are colonized Lactobacillus species, but levels can change dramatically over a month. Marked increases in G. vaginalis were during menses. Participants with BV have diverse communities of fastidious bacteria that are depleted by metronidazole therapy. Women with recurrent BV initially respond to antibiotic treatment with steep declines in concentrations, but these bacteria later reemerge, suggesting that antibiotic resistance in these bacteria is not an factor mediating BV recurrence.