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Rapid fluctuation of the vaginal microbiota measured by Gram stain analysis
  1. Rebecca M Brotman1,
  2. Jacques Ravel1,
  3. Richard A Cone2,
  4. Jonathan M Zenilman3
  1. 1University of Maryland School of Medicine, Institute for Genome Sciences, Baltimore, Maryland, USA
  2. 2Johns Hopkins University, Department of Biophysics, Baltimore, Maryland, USA
  3. 3Johns Hopkins School of Medicine, Bayview Medical Center, Division of Infectious Diseases, Baltimore, Maryland, USA
  1. Correspondence to Dr Rebecca M Brotman, Assistant Professor, Department of Epidemiology and Preventive Medicine, Institute for Genome Sciences, University of Maryland School of Medicine, BioPark Building II, 801 West Baltimore Street, Room Number 626, Baltimore, MD 21201, USA; rbrotman{at}


Background The aetiology of bacterial vaginosis (BV) remains unknown.

Objective To describe longitudinal changes in vaginal microbiota.

Methods Thirty-nine women (mean age 36.8 years; 22 (56.4%) African-American) self-collected vaginal specimens twice weekly for 16 weeks as part of a vaginal douching cessation study. In an analysis where each woman serves as her own control, conditional logistic regression was used to evaluate daily, time-varying factors associated with a woman's incident BV episode(s) as compared with her persistently BV-negative sample(s). BV was defined by a Nugent's Gram stain score ≥7.

Results 46.2% of participants had BV in the first 4 weeks of observation. Rapid fluctuation of vaginal microbiota was observed in 226 transitions to BV or spontaneous remission. Duration of BV was often short: 51% of the episodes lasted for only one sample interval (3 days). Among women who had at least one BV episode, the median number of episodes per woman was 8.7 (SD 7.4, range 1–22). Lubricant use 1 day before specimen collection (adjusted OR (aOR)=11.75, 95% CI 1.96 to 70.27) and rectal sex 2 days before (aOR=4.48, 95% CI 2.79 to 7.17) were associated with BV onset.

Conclusion Rapid fluctuation of the vaginal microbiota was seen. Longitudinal studies with long intervals between sampling are likely to miss episodes of BV. Recent report of lubricant use and rectal sex were associated with incident BV.

  • Bacterial vaginosis
  • Nugent score
  • Gram stain
  • vaginal microbiota
  • epidemiology

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  • Parts of this study were presented at the British Association for Sexual Health and HIV – American Sexually Transmitted Diseases Association 3rd Joint Conference, 7–10 May 2008, Brooklyn, NY, Oral presentation # O-20 and The International Society for Sexually Transmitted Disease Research, 18th Biennial Congress, 28 June 28–1 July 2009, London, poster # P4.137

  • Funding This study was supported by NIH grants: K12-RR023250 (to RMB), UH2-AI083264 (to JR), R03-AI061131 (to JMZ) and K24-AI001633 (to JMZ).

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the Johns Hopkins School of Medicine, University of Maryland School of Medicine.

  • Provenance and peer review Not commissioned; not externally peer reviewed.