Oral Sexual Exposures Can Lead to Viable Rectal Chlamydia trachomatis Infection

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.

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).

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).

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.