Clinical and epidemiological characteristics of Chlamydia trachomatis infection among sexually transmitted infection clinics patients.

Background: Chlamydia trachomatis (CT) infections are a public health problem because of its high incidence and consequences on reproductive health. Our aim is to describe the socio-demographic, behavioral and clinical characteristics of patients with CT infection in order to adapt preventive interventions for the highest risk groups.

Methods: Prospective case series of all patients diagnosed with CT between September 2016 and January 2019 in the reference STI clinics of Osakidetza (Basque Health Service) in Bizkaia (Spain).

Results: 847 patients (88.2%) agreed to participate: 41% women, 33.8% heterosexual men and 25% men who has sex with men (MSM); 33% were immigrants and 26% were under the age of 25 (33% of the women). Only 20% systematically used condoms. 36% had previously had STI and 28% had simultaneously another STI. 55% of the infections were asymptomatic (70% among women). In MSM, the rectum was affected in 69.5% of cases, the urethra in 31.4%, and the pharynx in 14.5%. The cervix was affected in 86.5% of the women, the rectum in 17.6%, and the pharynx in 13.8%. A contact study was only carried out in 58% of cases. The reinfection rate at 4 weeks was 17% among those with criteria to perform a test of cure.

Conclusion: Our results justify implement opportunistic screening in women under the age of 25 and young immigrants of both sexes, by taking genital and extragenital samples, as well as developing appropriate guidelines for the notification and follow-up of contacts.