Chlamydia infection in individuals reporting contact with sexual partners with chlamydia: a cross-sectional study of sexual health clinic attendees

Objectives We aimed to ascertain the proportion of positive, and predictive factors of chlamydia infection among females, heterosexual males and men who have sex with men (MSM) presenting to a sexual health service reporting contact with a chlamydia infected sexual partner. Methods A cross-sectional analysis of patients attending the Melbourne Sexual Health Centre from October 2010 to September 2013. Behavioural data obtained using computer assisted self-interview were analysed to determine factors predictive of chlamydia. Results Of the 491 female, 808 heterosexual male, and 268 MSM chlamydia contacts, the proportion diagnosed with chlamydia were 39.9% (95% CI 35.7% to 44.3%), 36.1% (95% CI 32.9% to 39.9%) and 23.5% (95% CI 18.8% to 29.0%), respectively. Female chlamydia contacts were more likely to have chlamydia if age <25 (adjusted OR (AOR) 1.86, 95% CI 1.12 to 3.10) or if they reported inconsistent condom use during vaginal sex with a regular male partner (AOR 2.5, 95% CI 1.12 to 6.14). Heterosexual male contacts were more likely to have chlamydia if age <25 (AOR 1.69, 95% CI 1.25 to 2.28) or if they had a regular female sexual partner (AOR 1.38, 95% CI 1.03 to 1.85). In MSM urethral chlamydia was diagnosed in 8.8%, rectal chlamydia in 20.2%, and 3.9% at both sites. MSM were more likely to have chlamydia if they had a regular male sexual partner (OR 2.12, 95% CI 1.18 to 3.81). Conclusions This study of female, heterosexual male, and MSM presentations with self-reported chlamydia contact provides insight into the likelihood and predictive factors of infection. The data may inform policy and individual clinical decision making regarding presumptive treatment of chlamydia contacts.