Objective: To help inform screening guidelines, we estimated the proportion of asymptomatic men who have sex with men (MSM) with oropharyngeal chlamydia.
Study design: An audit of asymptomatic MSM attending a sexual health service from March 2015 to April 2016 was conducted. They each had an oropharyngeal swab that was tested for Chlamydia trachomatis by transcription-mediated nucleic acid amplification. In addition, a random sample of 17 swabs that initially tested positive had confirmatory testing to determine the likelihood of true positivity.
Results: We collected 4877 oropharyngeal swabs: 72 (1.5%; 95% confidence interval [CI], 1.2-1.9) were diagnosed positive for chlamydia. Most (n = 56 [78%]; 95% CI, 67-86) only had oropharyngeal chlamydia detected (i.e., no concurrent extraoropharyngeal chlamydia and/or gonorrhea). Of the 17 samples that underwent confirmation, all confirmed positive (100%; 95% CI, 82-100).
Conclusions: Although oropharyngeal chlamydia prevalence was low among asymptomatic MSM, most oropharyngeal chlamydia cases had no chlamydia at other sites, and these cases would have been missed and not treated if routine oropharyngeal chlamydia testing was not done.