Incident urogenital and anorectal Chlamydia trachomatis in women: the role of sexual exposure and autoinoculation: a multicentre observational study (FemCure)

Abstract

BackgroundAnorectal infections with Chlamydia trachomatis (CT) are common in women visiting STI outpatient clinics. We here evaluated the risk posed by sexual exposure and by alternate anatomical site infection for incident anorectal and urogenital CT.MethodsProspective multicentre cohort study, FemCure. Participants were treated for CT, and after 4, 6, 8, 10 and 12 weeks, they self-collected anorectal and urogenital samples (swabs) for CT-DNA testing. We calculated the proportion with incident CT, that is, CT incidence (at weeks 6–12) by 2-week time-periods. Compared with no exposure (A), we estimated the risk of incident CT for (B) sexual exposure, (C) alternate site anatomic site infection and (D) both, adjusted for confounders and expressed as adjusted ORs with 95% CIs.ResultsWe analysed data of 385 participants contributing 1540 2-week periods. The anorectal CT incidence was 2.9% (39/1343) (95 CI 1.8 to 3.6); 1.3% (A), 1.3% (B), 27.8% (C) and 36.7% (D). The ORs were: 0.91 (95% CI 0.32 to 2.60) (B), 26.0 (95% CI 7.16 to 94.34) (C), 44.26 (95% CI 14.38 to 136.21) (D).The urogenital CT incidence was 3.3% (47/1428) (95% CI 2.4 to 4.4); 0.7% (A), 1.9% (B), 13.9% (C) and 25.4% (D). The ORs were: 2.73 (95% CI 0.87 to 8.61) (B), 21.77 (95% CI 6.70 to 70 71) (C) and 49.66 (95% CI 15.37 to 160.41) (D).ConclusionsAfter initial treatment, an alternate anatomical site CT infection increased the risk for an incident CT in women, especially when also sex was reported. This may suggest a key role for autoinoculation in the re-establishment or persistence of urogenital and anorectal chlamydia infections.

Controversies and evidence on Chlamydia testing and treatment in asymptomatic women and men who have sex with men: a narrative review

“…Evidence for autoinoculation has been provided in a mathematical model in women attending STI clinics, with a daily probability of 0.5-1% that a urogenital infection leads to a rectal infection, or vice versa [31]. This was also supported by prospective observational data (15-40 two-week follow-up periods) showing that urogenital CT, especially with high load, was strongly predictive of rectal CT acquisition two weeks later without sexual exposure [32].…”

“…Pharyngeal CT is not associated with reported oral sex. The spontaneous clearance between diagnosis and treatment is high: 36–57% (interval: 9–10 days) in men and women [ 24 , 32 , 89 ]. A study in MSM in Seattle estimated the median duration of pharyngeal CT at 6 weeks [ 100 ].…”

“…A study in MSM in Seattle estimated the median duration of pharyngeal CT at 6 weeks [ 100 ]. Spontaneous clearance is more common with low baseline bacterial load and in a single anatomic site CT, as is also established in urogenital and rectal CT [ 24 , 25 , 32 , 89 ]. The pharyngeal CT load is low and similar between men and women [ 18 ].…”

“…A Dutch modelling study estimated that more rectal CT in women who visited STI clinics was caused by autoinoculation from the urogenital to the rectal location than by anal sex [ 31 ]. Observational data also suggest that rectal CT may migrate between the rectal and vaginal site, by an autoinoculation process [ 32 ]. Women who reported intercourse or other sexual exposure risks (but who had not had a preceding rectal CT) had a urogenital 2-week incidence of 2%; this incidence was higher in women who had a preceding rectal CT (14% when they did not report sex, and 25% when they reported it) [ 32 ].…”

“…Observational data also suggest that rectal CT may migrate between the rectal and vaginal site, by an autoinoculation process [ 32 ]. Women who reported intercourse or other sexual exposure risks (but who had not had a preceding rectal CT) had a urogenital 2-week incidence of 2%; this incidence was higher in women who had a preceding rectal CT (14% when they did not report sex, and 25% when they reported it) [ 32 ]. Without the appropriate management of rectal CT, we can thereby hypothesise that rectal CT in women may comprise a ‘hidden’ reservoir of transmittable infections and play a role in sustaining CT, in line with an Australian modelling study [ 113 ].…”