Seek and you shall find! Prevalence and trends of chlamydial and gonococcal infections in a high-density urban area in Italy around the COVID era: a laboratory-based survey

Background A comprehensive understanding of the epidemiology of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections is essential for developing effective prevention strategies. This retrospective, laboratory-based study assessed the prevalence and trends of CT and NG infections in a densely populated area in northern Italy between 2018 and 2023. Methods We collected data on all samples submitted to the Microbiology of IRCCS Azienda Ospedaliero-Universitaria of Bologna for CT/NG testing. Data were stratified by year, sex, age, testing site and anatomical sampling site. Results A total of 63 569 samples from 46 501 individuals were analysed. CT prevalence was 7.2%, with a peak in those aged 18-25 and a male-to-female ratio of 1.56. Although one-third of tests were from family counselling centres or gynaecologists, the highest CT positivity was found at the STI outpatient clinic (69%) and infectious diseases centres (13%). NG prevalence was 4.8%, with very low rates in family and gynaecology settings. NG showed a striking male predominance (M:F=8.6). For both CT and NG, we observed (1) a rise in case numbers over time, especially in males; (2) a decline during the COVID-19 pandemic followed by a rebound; and (3) a notable proportion of pharyngeal and rectal infections. Conclusions This study highlights key epidemiological trends of CT and NG infections based on population characteristics, healthcare access points and the influence of external factors such as COVID-19 pandemic. These findings underscore the importance of targeted screening and prevention programmes and reinforce the role of laboratory-based surveillance to guide public health interventions.