The Cervicovaginal Microbiota in Women Notified for Chlamydia trachomatis Infection: A Case-Control Study at the Sexually Transmitted Infection Outpatient Clinic in Amsterdam, The Netherlands

Background. Increasing evidence suggests that the cervicovaginal microbiota (CVM) plays an important role in acquiring sexually transmitted infections (STIs). Here we study the CVM in a population of women notified by a sex partner for Chlamydia trachomatis infection. Methods. We included 98 women who were contact-traced by C. trachomatis-positive sex partners at the STI outpatient clinic in Amsterdam, the Netherlands, and analyzed their cervicovaginal samples and clinical data. CVMs were characterized by sequencing the V3/V4 region of the 16S ribosomal RNA gene and by hierarchical clustering. Characteristics associating with C. trachomatis infection were examined using bivariable and multivariable logistic regression analysis. Results. The CVM was characterized for 93 women, of whom 52 tested C. trachomatis positive and 41 C. trachomatis negative. We identified 3 major CVM clusters. Clustered CVM predominantly comprised either diverse anaerobic bacteria (n = 39 [42%]), Lactobacillus iners (n = 32 [34%]), or Lactobacillus crispatus (n = 22 [24%]). In multivariable analysis, we found that CVM was significantly associated with C. trachomatis infection (odds ratio [OR], 4.2 [95% confidence interval {CI}, 1.2-15.4] for women with diverse anaerobic CVM and OR, 4.4 [95% CI, 1.3-15.6], for women with L. iners-dominated CVM, compared with women with L. crispatus-dominated CVM), as was younger age (OR, 3.1 [95% CI, 1.1-8.7] for those = 21 years old) and reporting a steady sex partner (OR, 3.6 [95% CI, 1.4-9.4]). Conclusions. Women who tested positive for Chlamydia trachomatis infection after having been contact-traced by a chlamydia-positive partner were more likely to have CVM dominated by L. iners or by diverse anaerobic bacteria, than by L. crispatus.