Rectal infection with Chlamydia trachomatis (CT) is frequent in women who deny receptive anal sex and is thought to arise from autoinoculation of the rectum from vaginal secretions. An alternate hypothesis is that oral sex inoculates and establishes gastrointestinal tract infection. Distinguishing these hypotheses is difficult in women. In men, autoinoculation is unlikely and heterosexual men frequently perform oral sex, but rarely participate in receptive anal exposure behaviors.
We enrolled high-risk men with and without nongonococcal urethritis who presented to a sexually transmitted infection clinic in Indianapolis, Indiana. Urine and rectal swabs were collected and tested for urogenital and rectal CT, Neisseria gonorrhoeae (NG), and Mycoplasma genitalium (MG). Men completed surveys concerning symptoms, sexual orientation, and detailed recent and lifetime oral and anal sexual behaviors.
Rectal CT was detected in 2/84 (2.4%) heterosexual men who reported cunnilingus, but no lifetime receptive anal behaviors. All of the men who denied receptive anal behaviors were negative for rectal NG and MG. In homosexual and bisexual men, rectal CT prevalence was high (9.7%), and rectal NG (4.8%) and MG (4.8%) were also detected.
We detected rectal CT infections in heterosexual men who reported cunnilingus but denied receptive anal behaviors. Oral sex may be a risk factor for rectal CT infection via oral inoculation of the gastrointestinal tract.
We observed a low incidence of rectal Chlamydia trachomatis infection in heterosexual men.
From the *Division of Infectious Diseases, Department of Medicine,
†Department of Microbiology and Immunology,
‡Department of Biostatistics,
§Department of Pediatrics, Division of Adolescent Medicine, Indiana University School of Medicine, Indianapolis; and
¶Center for Sexual Health Promotion, Indiana University, Bloomington, IN
Acknowledgements: The authors thank Sara Hanson, Christina Davis, Virginia Caine, and the staff of the Indiana University Infectious Diseases Research Laboratory and the MCPHD Bell Flower Clinic for their assistance.
B.E.B. and D.E.N. are equal contributors.
Conflicts of Interest and Sources of Funding: This work was supported by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health grants [R01AI099278 and R01AI116706] to D.E.N. and the Indiana Clinical and Translational Sciences Institute, funded by a KL training awarded (UL1TR002529) from the National Institutes of Health, National Center for Advancing Translational Sciences, Clinical and Translational Sciences Award to S.J.J. The study funders had no role in the design; data collection, analysis or writing of this manuscript. All of the other authors declare no conflicts of interest.
Correspondence: David E. Nelson, Indiana University School of Medicine, Van Nuys Medical Sciences Building, MS 420, 635 Barnhill Drive, Indianapolis, IN 46202. E-mail: firstname.lastname@example.org.
Received for publication January 8, 2019, and accepted March 10, 2019.
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Online date: March 15, 2019