Introduction Alterations in vaginal microbiota associated with intrauterine contraception may impact host susceptibility to sexually transmitted infection. We evaluated the effect of the levonorgestrel intrauterine system (LNG-IUS) on cervical persistence of Chlamydia trachomatis (CT) in a baboon model and whether CT persistence was correlated with vaginal microbial community structure.

Methods 20 wild caught female olive baboons (Papio abubis) were randomly assigned to receive either LNG-IUS and CT inoculation (n = 8), LNG-IUS and sham inoculum (n = 2), CT inoculation alone (n = 8), or sham inoculation (n = 2). Animals were acclimated to the LNG-IUS for 24 weeks after which animals were cervically inoculated once weekly for 5 weeks. Vaginal swabs were collected weekly for microbiome analysis by 16S rRNA-encoding gene sequence analysis. Presence of CT in the cervical epithelium was confirmed with weekly nucleic acid amplification testing (NAAT) and culture.

Results Use of the LNG-IUS was significantly associated with positive CT culture (p = 0.04) but not NAAT (p = 0.07). Median time to cervical clearance of CT as detected by NAAT was 12.5 days (range 5–16) for LNG-IUS animals in comparison to 7 days (range 3–10) for non-implanted animals (p = 0.14). Similarly, median time to cervical clearance of CT by culture was 12 days (range 5–15) for LNG-IUS animals and 5 days (range 1–10) for non-implanted animals (p = 0.05). We did not detect significant within group differences between vaginal microbial community structure at baseline and following LNG-IUS insertion, CT inoculation, or LNG-IUS and CT in combination.

Conclusions Use of the LNG-IUS was associated with a trend towards cervical persistence of CT in a baboon model. However, this persistence is not explained by alterations in vaginal microbial communities.

Disclosure of interest statement The authors have no disclosures to report.