What would be missed if we didn't screen men who have sex with men for oral chlamydia trachomatis? A cross-sectional study.

UNLABELLED: Background This study aimed to describe oropharyngeal chlamydia (OCT) in gay and bisexually active men (GBM) attending a large urban sexual health clinic in Sydney and determine what proportion of cases would be missed if screening was not routine.

METHODS: Retrospective data were extracted for all GBM with a positive OCT result between 1 October 2012 and 31 April 2014. The control group consisted of patients who had a negative OCT result on their first visit during the study period, and each patient was only counted once.

RESULTS: A total of 74 of 2920 GBM (0.03, 95% CI: 0.02-0.03) were diagnosed with OCT. The 2920 GBM had a total of 11226 OCT tests performed, demonstrating OCT test positivity of 0.006 (95% CI: 0.005-0.008). A total of 62 sexually transmissible infections (STIs) were diagnosed at other sites: 34 rectal chlamydia (CT), 12 throat gonorrohea (GC), 7 urine CT, 7 rectal GC, 1 infectious syphilis and 1 non-gonoccal urethritis (NGU) case. Of the 74 OCT cases, 56 (0.76, 95% CI: 0.64-0.85) were treated with Azithromycin; 51 (69%) as part of standard treatment for their STI co-infection (34 rectal CT, 12 throat GC, 7 urine CT, 7 rectal GC, 1 NGU case) and a further five (7%) were treated as contacts. The remaining 18 people (0.24, 95% CI: 0.15-0.36) would not have been treated unless they were tested specifically for OCT.

CONCLUSION: Overall, two-thirds of the OCT cases received appropriate treatment and only a small number of cases would have been missed had routine screening not been performed. With an extremely low overall test positivity of 0.6%, screening for OCT at our service adds little to population level health control.