LAUSR

Chlamydia trachomatis (CT) causes pelvic inflammatory disease (PID) and other sequelae; however, these associations are not fully characterized. CT serologic assays including Pgp3 ELISA may detect prior CT infection and may better elucidate these associations. We used a serologic Pgp3 multiplex bead array assay (Pgp3MBA) to measure CT seroprevalence in reproductive-age US women and assess the association with PID. We performed CT Pgp3MBA on sera collected from women 18–39 years old during the 2013–2016 cycles of the National Health and Nutrition Examination Survey (NHANES) who had available urine CT nucleic acid amplification test results. Weighted Pgp3MBA CT seroprevalence and 95% confidence intervals (95% CI) were calculated. We also determined weighted prevalence ratios (PRs) and 95% CIs of self-reported lifetime PID among women with and without detectable Pgp3MBA and other characteristics to estimate these US national statistics. Among 2,339 women, 1,725 (73.7%) had available sera. Of these women, 1,425 (or 93.4% of those with data) were sexually experienced and had a CT seroprevalence of 35.9% (95% CI 33.4–38.4). When weighted for US women, CT seroprevalence was 30.5% (95% CI 26.6–34.4%), ranging from 16.9% (95% CI 11.0–22.8%) among non-Hispanic Asian women to 70.2% (95% CI 62.4–78.0%) among non-Hispanic black women. PID was reported by 4.2% (95% CI 3.1–5.2) of 1,413 sexually-experienced women with PID data or an estimated 3.8% (95% CI 2.6–5.0) of US women. Among US women, estimated PID varied by Pgp3MBA status; 7.3% (95% CI 4.3–10.2) of Pgp3MBA-positive women were estimated to report PID versus 2.3% (95% CI 1.3–3.4) of Pgp3MBA-negative women (PR 3.1; 95% CI 1.7–5.9). PID prevalence did not vary by age, nor self-reported recent sexually transmitted disease among US women, but was higher among non-Hispanic black women compared to non-Hispanic white women (PR 2.2; 95% CI 1.4–3.5). Nearly one-third of US women have had CT by Pgp3MBA, with differences by race/ethnicity. Women with prior CT had three times the reported PID prevalence of women without CT. Further serologic research may refine the population-level impact of CT prevention activities, such as recommended annual CT screening, on PID incidence, particularly among non-Hispanic black women. All Authors: No reported disclosures