Sharp increase in Chlamydia pneumoniae infections in 2024 in Germany

Chlamydia pneumoniae (C. pneumoniae) is a recognized cause of respiratory infections in children and adolescents, while it is often considered a negligible pathogen in adults outside of outbreaks. We performed a retrospective analysis from a nationwide surveillance network in Germany that collected data from 2018 to 2024. A multivariate analysis (binomial model) was performed to assess the influence of year, hospitalization status, gender and age on C. pneumoniae detection rate. Our analysis showed an increasing C. pneumoniae detection rate in 2024 compared to 2019, especially in children below 15 years and adults aged 30-50 years, mostly in patients who were treated as outpatients.