Abstract:

Objective To investigate the clinical characteristics of Chlamydia pneumoniae pneumonia in children and enhance awareness, diagnostic accuracy, and therapeutic management of this condition. Methods A retrospective analysis was performed on clinical data from children diagnosed with Chlamydia pneumoniae pneumonia admitted to the Department of Respiratory Medicine between July 2024 and May 2025. Results A total of 39 patients were included, comprising 20 males and 19 females, with a median onset age of 10.9 years (interquartile range: 7.8-12.5). The mean duration of illness prior to admission was (11±5) days, and the median hospital stay was 6 days (range: 4-6). All patients presented with cough; fever, chest pain, and chest tightness were observed in some, while only a few exhibited abnormal pulmonary auscultation findings. Chest CT revealed round high-density opacities or patchy consolidations, predominantly subpleural in distribution. Air bronchograms and halo signs were noted in a subset of cases. Unilateral lung involvement occurred in 34 patients, bilateral in 5. Laboratory findings showed normal white blood cell count, neutrophil percentage, procalcitonin, and IL-6 levels. Elevated C-reactive protein was present in 12.8% of patients, increased erythrocyte sedimentation rate in 50%, and elevated IL-10 in 73.7%. All 39 patients had positive serum IgM antibodies against Chlamydia pneumoniae; among them, 7 had positive Chlamydia pneumoniae nucleic acid detected by next-generation sequencing in bronchoalveolar lavage fluid, and 1 had a positive nucleic acid test in sputum obtained from an outside institution. Most patients received azithromycin monotherapy, followed by doxycycline; 5 patients additionally received glucocorticoids. Clinical recovery was achieved in all 36 follow-up cases. Conclusions Pediatric Chlamydia pneumoniae pneumonia may manifest without fever, with cough as the sole presenting symptom. Characteristic imaging features include subpleural, mass-like consolidations often accompanied by peripheral air bronchograms and occasionally halo signs. Definitive diagnosis relies on serological IgM detection or nucleic acid testing. Treatment with azithromycin or doxycycline is effective.

Key words: Chlamydia pneumoniae, IL-10, chest CT, child