Oral Sexual Exposures Can Lead to Viable Rectal Chlamydia trachomatis Infection

Background: Chlamydia trachomatis (CT) acquired orally may survive passage through the gastrointestinal tract and establish an infection in the rectum, but how often this occurs is unknown.

Methods: In 2019 to 2022, we enrolled individuals assigned male at birth who reported sex with men and denied receptive anal sex in the past 2 years. Participants enrolled at the Seattle Sexual Health Clinic or online. Participants completed a behavioral survey and self-collected rectal swabs for CT nucleic acid amplification testing (NAAT) and culture and viability polymerase chain reaction (vPCR). We defined oral exposures as fellatio, cunnilingus, and oral-anal (i.e., rimming).

Results: We enrolled 275 men; 60 (22%) reported only oral exposures in the past 12 months. Of these, 5 (8.3%) tested positive for rectal CT by NAAT; 1 (2%) had viable CT detected (culture positive; vPCR positive). Another 43 participants reported only oral exposures in the past 2 months, but rectal exposures 3 to 12 months ago. Of these, 4 (9%) tested NAAT positive for rectal CT; 1 had viable CT detected (culture negative; vPCR positive).

Conclusions: Passage of CT from the mouth to the rectum occurs but is most often nucleic acid remnants rather than viable bacteria. Nonetheless, it seems possible to establish a viable rectal CT infection via oral exposures.