Chlamydia trachomatis Incidence in Relation to Vaginal Microbiota Dynamics, Immunogenetics and Exposures in a Cohort of Young Student Women in France.

BACKGROUND

Given the potential role of the vaginal microbiota in the acquisition of Chlamydia trachomatis infections, we aim to investigate its contribution together with immunogenetics and epidemiological exposures to the incidence of C. trachomatis in young women.

METHODS

This study involved 313 female students aged 18-24 years from the i-Predict prevention trial in France. Participants provided 4 self-collected vaginal samples and filled 4 self-administered questionnaires every 6 months for 18 months. C. trachomatis-positive participants and negative controls with complete follow-up were selected for this analysis and submitted to chlamydia testing and to vaginal microbiota characterization using 16S rRNA amplicon sequencing. Thirteen human single nucleotide polymorphisms (SNPs) related to C. trachomatis susceptibility and severity were also assessed.

RESULTS

Compared with 260 noninfected participants, Gardnerella spp., Fannyhessea vaginae and Prevotella timonensis were more abundant in C. trachomatis-incident participants (n = 24) before infection. Having a CST IV at the preceding sample compared with a CST I (OR 3.77, 95%CI [1.12-12.69], P = .033) was associated with increased risk of C. trachomatis acquisition, as well as having had multiple concomitant partners in the last 6 months (5.40 [2.10-13.92], P < .001). Lifetime condom use was associated with decreased incidence (0.38 [0.15-0.95], P = .039). None of the tested human SNPs was associated with C. trachomatis infection.

CONCLUSIONS

In this low-risk for C. trachomatis population, having a CST IV vaginal microbiota and associated bacterial anaerobes was a risk factor for C. trachomatis acquisition after adjustment for other exposures. Condom use remains one of the main tools to prevent incidence. Clinical Trials Registration.  ClinicalTrials.gov Identifier: NCT02904811. Registration date: 19 September 2016.