Chlamydia trachomatis serovars in community-based HIV-positive and HIV-negative men who have sex with men in Sydney, Australia

Objectives There are few data on the distribution of specific Chlamydia trachomatis serovars among men who have sex with men (MSM) outside clinical settings. To investigate these patterns, serovar determination was performed on chlamydia-positive samples from two community-based cohort studies of HIV-positive and HIV-negative MSM in Sydney, Australia. Methods From January 2005 to June 2007 all positive C trachomatis pharyngeal, urine and anal samples were evaluated. The serovar of each C trachomatis infection was determined by omp1 gene sequencing with confirmatory quantitative PCR screening. Symptom data were routinely reported by study participants at the time of testing. Results Serovar determination was possible for 54 samples among 52 participants. Seven samples were not able to be typed. Site-specific symptoms were reported by fewer than 10% of participants diagnosed with pharyngeal and anogenital chlamydia. The most commonly identified serovars were serovar D (n=32, 59.3%, 95% CI 45.0 to 72.4), followed by serovar G (n=11, 20.4%, 95% CI 10.6 to 33.5) and serovar J (n=5, 9.3%, 95% CI 3.1 to 20.3). Only one lymphogranuloma venereum serovar was identified (L2b). Conclusions This community-based study found a similar distribution of chlamydia serovars to that observed among Australian community-based MSM several years ago, and serovar distribution recently observed among predominantly symptomatic MSM at a Sydney clinic. These findings suggest little change in C trachomatis serovar distribution in Australian MSM over the past decade and a lack of correlation of specific chlamydia serovars with anogenital symptoms among MSM.