Clinical significance of Chlamydia trachomatis and HPV coinfection across cervical lesion severity: a 10-year retrospective study in Southern China.

BACKGROUND: Persistent high-risk HPV infection is the major cause of cervical carcinogenesis, but the clinical relevance of Chlamydia trachomatis (CT) coinfection remains uncertain. We examined the epidemiological patterns of CT-HPV coinfection and their associations with cervical lesion severity among women in Southern China. METHODS: This retrospective study included 21,275 outpatients who underwent concurrent HPV genotyping, CT PCR testing, and cytological or histopathological evaluation between 2015 and 2024. Age-specific patterns and temporal trends were assessed. Age-adjusted logistic regression was used to examine associations of HPV and CT with cervical lesion categories. Six DNA methylation markers were analyzed in a subset of samples. RESULTS: Overall prevalence was 25.7% for HPV, 8.7% for CT, and 3.8% for HPV-CT coinfection, with declining trends over time. CT infection and HPV-CT coinfection were more common in younger women. HPV positivity was significantly higher in CT-positive than CT-negative women (43.9% vs 23.9%, p < 0.001). CT infection and coinfection were more frequently observed in ASC-US/-H and LSIL, while CT showed weaker associations with advanced lesions and was not significantly associated with invasive cervical carcinoma. Among the six methylation markers, only PAX1 showed significant differences among the three groups, while HPV-CT coinfection was not associated with additional methylation alterations compared with HPV infection alone. CONCLUSIONS: CT infection and HPV-CT coinfection were concentrated in younger women and were more frequently associated with low-grade cervical abnormalities. CT positivity was also associated with a higher prevalence of HPV infection.