Related Experiment Video
Updated: May 27, 2026

Models of Murine Vaginal Colonization by Anaerobically Grown Bacteria
Published on: May 25, 2022
Effect of sexual activity on vaginal colonization with hydrogen peroxide-producing lactobacilli and Gardnerella
Caroline Mitchell1, Lisa E Manhart, Katherine K Thomas
1Department of Obstetrics & Gynecology, University of Washington, Seattle, WA 98195, USA. camitch@uw.edu
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.
Related Concept Videos
Microbiota of the Urogenital Tract
Surface Membrane Barriers
The outer layer of the skin, the epidermis, is a robust barrier comprising layers of closely packed keratinized cells. This dense arrangement prevents microbes from penetrating the body. The periodic shedding of epidermal cells...
Vagina
Development of the Oral Microbiota
Development of Human Microbiota
The Oral Microbiota

