Simplified Chlamydia trachomatis screening in France: positivity rate from a large community laboratory network in 2025

In France, Chlamydia trachomatis (Ct) infections have steadily increased since the late 1990s, particularly among young adults. To improve access to screening, the national prescription-free testing program, 'Mon Test IST' (MTI), was introduced in 2024, providing direct and largely reimbursed screening for five sexually transmitted infections in private laboratories. This study aimed to estimate Ct test positivity in 2025 within the Biogroup laboratory network and to identify factors associated with the use of the MTI program, with a particular focus on individuals aged between 18 and 25 years, inclusive.

Within the MTI pathway, a standardized questionnaire collected information on symptoms, risk factors and sexual practices, allowing adaptation of sampling sites (systematic urogenital testing with additional pharyngeal and/or anal sampling when relevant). Pseudonymized data from >900 Biogroup laboratories (approximately 25% of the French private medical laboratory sector) were extracted for 2025 across five major regions. Analyses included descriptive statistics, chi-squared tests and logistic regression with a significance level of 0.05.

In 2025, 313,585 screenings were performed with a prescription and 230,022 through MTI. MTI was used by 56.3% of patients aged 18-25 years compared with 34.6% of patients aged ≥26 years (P < 0.0001). Young men were more likely than young women to use the prescription-free pathway (61.6% vs 52.6%; OR 1.45, 95% CI 1.42-1.48). Overall Ct test positivity was 5.1%, reaching 8.1% in individuals aged 18-25 years. Among asymptomatic young individuals without reported risk factors, Ct test positivity remained notable (4.4% in women, 3.9% in men). In multi-site testing, 13.3% of infections would have been missed with urogenital sampling alone.

The MTI program effectively reaches young individuals with high Ct test positivity, including those who do not perceive themselves at risk. Prescription-free access combined with practice-adapted sampling appears to be a valuable strategy to strengthen Ct screening in France.