Clinical characteristics of children hospitalized with Chlamydia pneumoniae pneumonia

Background: Chlamydia pneumoniae is an atypical respiratory pathogen that contributes to community-acquired pneumonia in children. However,the clinical manifestations are often non-specific, posing challenges for early identification. The purpose of this study is to summarize the Clinical characteristics of Chlamydia pneumoniae pneumonia in children,thereby facilitating its recognition prior to the availability of pathogen detection results. Methods: Children hospitalized with community-acquired pneumonia between January 1, 2023 to April 30, 2025 in the Department of Respiratory Medicine,Children’s Hospital of Soochow University were enrolled. Nasopharyngeal aspirates or BALF were collected for respiratory pathogen detection and medical records of C. pneumoniae infection were retrospectively collected. Results: Of 15144 hospitalized children with community-acquired pneumonia, 260(1.71%,260/15144) had C. pneumoniae infection.After exclusions criteria, 226 cases with complete data were analyzed.Among the 226 children,the male-to-female ratio was 2:1 with a median age of 11.2 (9.5-13.0)years.Of which,206 (91.15%) patients were aged between 6–15 years old .The average length of hospital stay was 6.54±1.59 days.The most common symptoms were cough (100%), yellow sputum (42.60%),fever (39.38%).The median duration from onset to admission was 7(5.0,10.0)days and median pre-admission fever durations of 5.0(3.0,7.0)days. Radiological examination showed that 95.13% had pulmonary parenchymal changes; 9.64% had unilateral involvement.,mostly in the right lower lobe (31.85%)and 49 left lower lobes(21.68%). Lesions in ≥2 lobes occurred in 6.64% Complications included atelectasis（3.98%）,pleural effusion（3.54%）,and bronchiectasia（1.33%）. All cases were treated with azithromycin or doxycycline，51 cases (22.56%)received fiberoptic bronchoscopy and lavage treatment,with full recovery and no severe outcomes. Conclusion: The detection of C. pneumoniae in children has an increasing trend.C. pneumoniae pneumonia mainly occurs in 6–15-years, characterized by cough, yellow sputum, fever, unilateral lower-lobe parenchymal changes on imaging. Inflammatory markers are normal, complications rare. Macrolides/doxycycline work well with good outcomes.