Prevalence and Characterization of Undiagnosed Youths at Risk of Chlamydia trachomatis Infection: A Cross-sectional Study

The aim of this study was to determine the prevalence of Chlamydia trachomatis infection in undiagnosed young people aged between 15 and 24 years. MATERIALS AND METHODS: A convenience sample of 623 youths, with a mean (SD) age of 20.1 (2.2) years, was recruited from key spaces in the North Metropolitan area of Barcelona in Catalonia, Spain. Participants completed a 21-item questionnaire and provided a urine sample or vaginal swab for testing. RESULTS: The most common age at the first sexual intercourse was 16 years (24.6%), followed by 15 years (21.3%). Only 32.6% reported always use of condoms, 49.2% sometimes, and 15.6% never. A positive test for chlamydia was found in 34 participants (5.5%; 95% CI, 3.8–7.5), with no difference by sex. A positive test was significantly more common among the participants who were working, who had been diagnosed with a sexually transmitted disease (STD) at some point in their life, and who used web pages/apps to find new sexual partners more than once a month. In the multivariate analysis, working status was an independent factor associated with chlamydial infection (adjusted odds ratio[OR], 8.88; 95% CI, 1.71–46.17), whereas not having been previously diagnosed with an STD (OR, 0.34; 95% CI, 0.07–1.49) and never using the Internet to find sexual partners (OR, 0.16; 95% CI, 0.03–080) were protective factors against chlamydial infection. CONCLUSIONS: The prevalence of C. trachomatis infection was 5.5%. Working status, a previous diagnosis of STD, and use of the Internet to find new sexual partners were associated with chlamydial test positivity.