Clinical, Behavioral Characteristics of Women With Lactobacillus iners- Dominated Vaginal Microbiota

woman holding out condom
Close up shot of woman hand holding a small condom before using it with her lover
Study finds that information on unprotected intercourse practices, number of sexual partners, and education level may help identify women with Lactobacillus iners-dominated vaginal microbiota.

Results of a study suggest that information on unprotected intercourse practices, number of sexual partners, and education level may help identify women with Lactobacillus iners-dominated vaginal microbiota (community state type [CST], III). These findings were published in Sexually Transmitted Infections.

Between 2012 and 2014, researchers conducted a cross-sectional study to assess the clinical, sociodemographic, and behavioral characteristics associated with L iners-dominated vaginal microbiota among women in Brazil. Eligible patients included women of reproductive age (age range, 18-50 years) who presented for routine cervical cancer screening at primary healthcare clinics. Patients with a current urinary tract infection, those who were pregnant, and those who reported use of an intrauterine device or immunosuppressive therapy were excluded from the study. To determine vaginal microbiota characteristics, the researchers analyzed patients’ vaginal swab specimens that were obtained at least 5 days after their last menstrual period and 3 days after they last engaged in sexual intercourse. In addition, Clinical history and information on sociodemographic and behavioral characteristics were obtained via face-to-face interviews and a structured questionnaire.

Among a total of 442 patients included in the study, 222 had L iners-dominated vaginal microbiota, and 220 had vaginal microbiota dominated by another Lactobacillus spp. Patients with vaginal micribota dominated by another Lactobacillus spp included those with L crispatus (CST I), L gasseri (CST III), and L jensenii (CST V). In addition, the median patient age was 34 years and more than 50% were Black. The researchers found that the proportion of patients with CST III who completed high school was decreased compared with those with CST I, II, or V (52.7% vs 66.4%, respectively; P = .003). In addition, 94.5% of patients with CST I, II, and V reported a diet that included milk and dairy products, and the rate of condom use was decreased among those with CST III vs those with CST I, II, or V (29.3% vs 40.0%; P = .018). Patients with CST III were also more likely to have had 2 or more sexual partners prior to enrollment vs those with other CSTs (11.3% vs 5.0%; P = .009).

Among patients included in the study, the researchers found that the prevalence rates for species of Candida trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis were 4.1%, 0.4%, and 0.2%, respectively. On multivariable analysis, the researchers found an independent association between patients with CST III and having either 2 or more sexual partners (odds ratio [OR], 2.52; 95% CI, 1.20-5.27) or the presence of Candida spp on vaginal smears (OR, 2.24; 95% CI, 1.02-4.89).

This study was limited by its cross-sectional design which limited the ability to assess causal links between patient characteristics and type of vaginal microbiota.

The researchers concluded that “additional studies are needed to identify novel strategies to regulate the vaginal microbiota to ensure a protective and beneficial environment for women’s reproductive health.”

Disclosure: Some author(s) declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of disclosures.


Novak J, Ravel J, Ma B, et al. Characteristics associated with Lactobacillus inersdominated vaginal microbiota. BMJ Sex Transm Infect. 2021;0:1–7. doi:10.1136/sextrans-2020-054824