Rapid and Profound Shifts in the Vaginal Microbiota Following Antibiotic Treatment for Bacterial Vaginosis

J Infect Dis. 2015 Sep 1;212(5):793-802. doi: 10.1093/infdis/jiv079. Epub 2015 Feb 12.


Background: Bacterial vaginosis (BV) is a common polymicrobial disease associated with numerous negative reproductive health outcomes, including an increased risk of human immunodeficiency virus acquisition. BV is treatable with antibiotics, but relapse is common. A more detailed understanding of bacterial dynamics during antibiotic therapy for BV could identify conditions that favor establishment, maintenance, and eradication of BV-associated bacterial species, thereby improving treatment outcomes.

Methods: We used mathematical models to analyze daily quantitative measurements of 11 key bacterial species during metronidazole treatment for 15 cases of BV.

Results: We identified complete reorganization of vaginal bacterial composition within a day of initiating therapy. Although baseline bacterial levels predicted a longer time to clearance, all anaerobic species were eliminated rapidly within a median of 3 days. However, reemergence of BV-associated species was common following treatment cessation. Gardnerella vaginalis, a facultative anaerobe, was cleared more slowly than anaerobic BV-associated species, and levels of G. vaginalis often rebounded during treatment. We observed gradual Lactobacillus species growth, indicating that untargeted microbes fill the transient vacuum formed during treatment.

Conclusions: Under antibiotic pressure, the human microbiome can undergo rapid shifts on a scale of hours. When treatment is stopped, BV-associated bacteria quickly reemerge, suggesting a possible role for intermittent prophylactic treatment.

Keywords: Gardnerella vaginalis; Lactobacillus; bacterial vaginosis; mathematical modeling; metronidazole; qPCR; vaginal microbiota.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anti-Bacterial Agents / therapeutic use*
  • Bacteria / drug effects*
  • Bacteria / isolation & purification
  • Biota / drug effects*
  • Female
  • Humans
  • Longitudinal Studies
  • Metronidazole / therapeutic use*
  • Models, Theoretical
  • Time Factors
  • Vagina / microbiology*
  • Vaginosis, Bacterial / drug therapy*


  • Anti-Bacterial Agents
  • Metronidazole