Concordance of gonorrhoea of the rectum, pharynx and urethra in same-sex male partnerships attending a sexual health service in Melbourne, Australia

BACKGROUND We aimed to describe anatomic site-specific concordance of gonococcal infections in partnerships of men who have sex with men (MSM). METHODS We conducted a cross-sectional analysis of data from MSM partnerships attending Melbourne Sexual Health Centre between March 2011 and February 2015. Logistic regression models (random effect) were used to examine the association between gonococcal infections of the urethra, rectum and pharynx. Gonococci were detected by culture at all anatomic sites. RESULTS The analysis included 495 partnerships. Of the men with urethral gonorrhoea, 33% (95% CI 18-52) had partners with pharyngeal gonorrhoea and 67% (95% CI 48-82) had partners with rectal gonorrhoea. The adjusted odds of having urethral gonorrhoea was 4.6 (95% CI 1.2-17.1) for a man whose partner had pharyngeal gonorrhoea, and 48.1 (95% CI 18.3-126.7) for a man whose partner had rectal gonorrhoea. Of the men with rectal gonorrhoea, 46% (95% CI 31-61) had a partner with urethral gonorrhoea and 23% (95% CI 12-37) had a partner with pharyngeal gonorrhoea. The adjusted odds of having rectal gonorrhoea was 63.9 (95% CI 24.7-165.6) for a man whose partner had urethral gonorrhoea. Of the men with pharyngeal gonorrhoea, 42% (95% CI 23-63) had a partner with rectal gonorrhoea and 23% (95% CI 9-44) had a partner with had a partner with pharyngeal gonorrhoea. The adjusted odds of having pharyngeal gonorrhoea was 8.9 (95% CI 3.2-24.6) for a man whose partner had rectal gonorrhoea. The crude odds of having pharyngeal gonorrhoea was 14.2 (95% CI 5.1-39.0) for a man whose partner had pharyngeal gonorrhoea. CONCLUSIONS These data provide the first estimates of concordance of anatomic site-specific gonococcal infections in MSM partnerships, and confirm that urethral gonorrhoea is contracted from both rectal and pharyngeal sites, and suggest that gonococci transmit between the rectum and pharynx. However, due to use of culture rather than NAAT, our analysis was not adequately powered to assess pharynx-to-pharynx transmission of gonococci.