Chlamydia trachomatis genotypes among men who have sex with men in Australia

Sex Transm Dis. 2011 Apr;38(4):279-85. doi: 10.1097/OLQ.0b013e3181fc6944.


Background: Chlamydia trachomatis is a common bacterial sexually transmitted infection in men who have sex with men (MSM), although little is known about its distribution in Australian MSM communities.

Methods: From 2004 to 2008, 612 consecutive C. trachomatis positive anal swab and urine samples were collected for genotyping and quantification from MSM attending 2 sexual health centers (Melbourne and Sydney).

Results: The most common serovars detected were D (35.2%), G (32.7%), and J (17.7%), although these distributions changed significantly by year and city. C. trachomatis infections (2.8%) involved more than 1 serovar and only 1 lymphogranuloma venereum isolate was detected. The majority of serovar strains showed an identical omp1 genotype, with only 7.5% showing genotypic variability. Serovar G infections were not associated with overseas sexual activity; whilst individuals with serovar J were less likely to have had a prior C. trachomatis infection, and with serovar E were those who had prior C. trachomatis infection. Symptoms were present in 68% of urethral infections and 28% anal infections, and were associated with gonorrheal coinfection (13.8%), prior C. trachomatis infection (20.6%) and increasing age. A higher C. trachomatis load was identified in anal samples versus urine (1.48 × 10(4) genome copies/anal swab; 3.72 × 10(3) copies/mL urine) and no association was made to concentration including the presence of symptoms and prior C. trachomatis infection.

Conclusions: This is the largest study of C. trachomatis serovars in MSM: it is the first to report C. trachomatis rectal loads, and provides an overview on C. trachomatis serovars and genotypic variants that circulate in Australian MSM communities.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Anal Canal / microbiology
  • Anus Diseases / diagnosis
  • Anus Diseases / epidemiology*
  • Anus Diseases / microbiology
  • Chlamydia Infections / diagnosis
  • Chlamydia Infections / epidemiology*
  • Chlamydia Infections / microbiology
  • Chlamydia trachomatis / classification*
  • Chlamydia trachomatis / genetics
  • Chlamydia trachomatis / isolation & purification
  • Cohort Studies
  • Coinfection / microbiology
  • Genotype
  • Homosexuality, Male*
  • Humans
  • Male
  • Middle Aged
  • New South Wales / epidemiology
  • Prevalence
  • Serotyping
  • Sexual Behavior
  • Sexual Partners
  • Urethra / microbiology
  • Urethral Diseases / diagnosis
  • Urethral Diseases / epidemiology*
  • Urethral Diseases / microbiology
  • Victoria / epidemiology
  • Young Adult