Effect of sexual activity on vaginal colonization with hydrogen peroxide-producing lactobacilli and Gardnerella vaginalis

Sex Transm Dis. 2011 Dec;38(12):1137-44. doi: 10.1097/OLQ.0b013e31822e6121.


Background: Bacterial vaginosis is associated with sexual activity, but mechanisms for this association are unclear.

Study design: Cross-sectional analysis of data from women reporting sex with women who provided information on sexual behaviors as part of a study of vaginal bacteria was conducted. Vaginal bacteria were detected by semiquantitative culture. Binomial regression with log-link evaluated associations between detection of bacteria and sexual behaviors reported to occur before enrollment. Linear regression evaluated associations between these behaviors and quantity of bacteria.

Results: Of the 320 women, 216 (68%) were colonized with H2O2-producing lactobacilli and 142 (44%) with Gardnerella vaginalis. Colonization with G. vaginalis was associated with >20 digital-vaginal sex acts (risk ratio, 2.01; 1.22, 3.29) or >10 toy-vaginal acts in the past 3 months (risk ratio, 1.76; 1.32, 2.36). Quantity of H2O2-producing lactobacilli was 1.3 log lower in colonized women reporting >10 acts of insertive vaginal sex-toy use in the past 3 months (95% confidence interval: -2.04, -0.56), 1.19 log lower with toy-vaginal sex in past 7 days (-1.75, -0.62), and 0.78 log lower in women sharing toys with a partner (-1.25, -0.31).

Conclusions: Vaginal insertive use and sharing of sex toys were associated with decreased quantities of H2O2-producing lactobacilli and higher risk of colonization with G. vaginalis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Bacterial Load
  • Culture Media
  • Female
  • Gardnerella vaginalis / growth & development*
  • Gardnerella vaginalis / isolation & purification
  • Homosexuality, Female
  • Humans
  • Hydrogen Peroxide / metabolism*
  • Lactobacillus / growth & development
  • Lactobacillus / isolation & purification
  • Lactobacillus / metabolism*
  • Sexual Behavior / physiology*
  • Vagina / microbiology*
  • Vaginosis, Bacterial / microbiology*
  • Young Adult


  • Culture Media
  • Hydrogen Peroxide