O10.1 Incident urogenital and anorectal Chlamydia trachomatis in women: the role of sexual exposure and auto-inoculation; a multicentre observational study (FemCure)

Abstract

<h3>Background</h3> Anorectal infections with Chlamydia trachomatis (CT) are prevalent in women visiting STI-clinics. In women, azithromycin treatment in anorectal chlamydia is unsuccessful in about 20%, with the potential of subsequent re-infection of the vagina through autoinoculation. We evaluated the risk for incident urogenital CT, by exposure from the own anorectal site and exposure by sex; and similarly evaluated risks for incident anorectal CT. <h3>Methods</h3> Prospective multicenter cohort study, FemCure. At 4, 6, 8, 10, and 12 weeks after azithromycin or doxycycline CT treatment, women self-collected anorectal and urogenital swabs for CT-DNA testing. We calculated the proportion with incident CT, at week 6–12, by 2-week time-periods. Compared to no exposure (A), risk of incident urogenital CT was estimated for sexual exposure (B), anorectal CT exposure (C), and both exposures (D), adjusted for confounders by adjusted odds ratios (OR) and 95% confidence intervals (CI). We similarly assessed incident anorectal CT. <h3>Results</h3> Data comprised 385 participants contributing 1540 two-week periods. Urogenital incidence was 3·3% (47/1428) [95%CI: 2·4–4·4]; 0·7% (A), 1·9% (B), 13·9% (C), and 25·4 (D). ORs were: 2·7 [95%CI:0·9–8·6] (B), 21·8 [95%CI:6·7–70·7] (C), 49·7 [95%CI:15·4–160·4] (D). Anorectal incidence was 2·9% (39/1343) [95CI:1·8–3·6]; 1·3% (A), 1·3% (B), 27·8% (C), and 36·7% (D). ORs were: 0·91 [95%CI:0·32–2·60] (B), 26·0 [95%CI:7·16–94·34] (C), 44·3 [95%CI:14·4–136·2] (D). Of incident CT, 55% urogenital and 70% anorectal infections persisted (&gt;two weeks). <h3>Conclusion</h3> Between 6–12 weeks after initial treatment, the risk for incident urogenital CT in women increased when women had a recent anorectal CT, especially when also sex was reported. Likewise, the risk for incident anorectal CT increased with urogenital CT and sex exposure. Findings may suggest a key role for auto-inoculation in the re-establishment or persistence of urogenital and anorectal chlamydia infections in treated women, especially in case of suboptimal initial treatment or lack of anorectal testing.