Vaginitis and Sexually Transmitted Infections Coinfections

To evaluate the prevalence and risk of concurrent sexually transmitted infections (STIs), Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, and Mycoplasma genitalium, among women with laboratory-confirmed bacterial vaginosis (BV) or vulvovaginal candidiasis (VVC).

This retrospective cross-sectional study included more than 1.5 million women 15 years of age or older who underwent molecular testing for BV, VVC, C trachomatis, N gonorrhoeae, or T vaginalis from 2022 to 2024; a subset of the study population of more than 37,000 women also underwent molecular testing for M genitalium. Analyses included a single BV test performed during the study period and excluded prior-year BV testing or multiple tests. Testing for other STIs within 7 days of a BV result was considered a testing event. Positivity and coinfection rates with 95% CIs were estimated and stratified by age and geographic region. Multivariate logistic regression estimated adjusted odds of STI positivity according to BV and VVC status.

Overall BV and VVC positivity rates were 38.7% and 28.5%, respectively; 10.8% of patients were positive for both. Among BV+ women, 12.0% had at least one STI (10.9% with only one STI and 1.1% with two-four STIs), whereas among BV- women, 3.8% had at least one STI (3.6% with only one STI and 0.2% two-four STIs) (P<.001). After adjustment for age, geographic region, and VVC results, BV+ status was significantly associated with increased odds of a positive C trachomatis (OR 2.8, 95% CI, 2.8-2.9), N gonorrhoeae (OR 3.8, 95% CI, 3.6-4.0), T vaginalis (OR 3.6, 95% CI, 3.6-3.7), and M genitalium (OR 1.9, 95% CI, 1.8-2.1) (all P<.001).

Among U.S. women presenting for vaginitis evaluation, BV is strongly and independently associated with increased risk of nonviral STI coinfection, whereas VVC is not. These findings support comprehensive STI testing in women with BV to optimize clinical management and to reduce reproductive health complications.