Only recent sexual partners contribute to oropharyngeal gonorrhoea positivity: the number of sexual partners over different time periods as an indicator of gonorrhoea and chlamydia infection duration among men who have sex with men.

Background Mathematical models have demonstrated that the majority of gonococcal transmission is from oropharynx to oropharynx (i.e. kissing) among men who have sex with men (MSM). The aim of this study is to investigate the association between the number of partners within specific time periods and gonorrhoea and chlamydia positivity.
Methods: This was a retrospective data analysis of MSM attending the Melbourne Sexual Health Centre between 2007 and 2016. Univariable and multivariable logistic regression analyses, with generalised estimating equations (GEE), were performed to determine if the number of partners within specified time periods was associated with site-specific gonorrhoea and chlamydia positivity.
Results: There were 45933 consultations which included 15197 MSM. Oropharyngeal gonorrhoea positivity was associated with the number of partners in the past 3 months, but not the number of partners 4-12 months ago; men who had ≥6 partners in the past 3 months had significantly higher odds of acquiring oropharyngeal gonorrhoea (aOR 1.93; 95% CI 1.61-2.31), but this was not the case for men who had ≥6 partners 4-12 months ago. Anorectal gonorrhoea and chlamydia and urethral chlamydia were associated with the number of partners in both time periods after adjusting for age and condom use.
Conclusions: The association of oropharyngeal gonorrhoea with the number of recent partners, but not partners from an earlier period, unlike anorectal gonorrhoea and anorectal and urethral chlamydia, could be explained by a shorter duration of oropharyngeal gonococcal infection. Annual screening for gonorrhoea may be insufficient to materially reduce oropharyngeal prevalence.