Clinical manifestations and epidemiology of the new genetic variant of Chlamydia trachomatis.

BACKGROUND: In 2006, a new genetic variant of Chlamydia trachomatis (nvCT) was discovered in Sweden. Clinical manifestations of this infection were studied in a high-risk population.

METHODS: During 2007, a prospective case-control study on sexual lifestyle and urogenital infections was performed at the Centre for Sexual Health (CSH), affiliated to Malmo University Hospital. A total of 629 C. trachomatis positive cases and 1252 negative controls were included. At Malmo University Hospital, Department of Obstetrics and Gynecology, all cases of pelvic inflammatory disease (PID) were assessed and correlated to the prevalence of nvCT.

RESULTS: Patients with nvCT or wild type C. trachomatis (wtCT) infection did not differ regarding their sexual lifestyle. Men with nvCT or wtCT infection did not differ in uro-genital symptoms or clinical findings. Women with nvCT infection reported painful urination (12.2% vs. 25.8%, P = 0.02) and were diagnosed with urethritis (11.1% vs. 40.0%, P = 0.04) less often than women with wtCT infection. The ratio of lower abdominal pain in women with nvCT infection was only half of that in women with wtCT infection (13.4% vs. 27.8%, P = 0.02). PID was detected in 0.8% of women with C. trachomatis infection in Malmo. All these cases were due to wtCT infection.

CONCLUSIONS: Symptomatic urethral infection and lower abdominal pain was less common in women with nvCT as compared to wtCT. Infection with nvCT was more frequently asymptomatic suggesting a possible difference in virulence between the nvCT strain and the wtCT strain.