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Comparative Study
. 2025 Aug 7;25(1):993.
doi: 10.1186/s12879-025-11405-4.

Comparative analysis of Chlamydia pneumoniae pneumonia (CPP) and Mycoplasma pneumoniae pneumonia in children and risk factors of severe CPP

Yu Huang  1 , Yi Chen  1 , Min Liu  1 , Lan-Fang Tang  1 , Lan-Fang Tang  2
Affiliations
Comparative Study

Comparative analysis of Chlamydia pneumoniae pneumonia (CPP) and Mycoplasma pneumoniae pneumonia in children and risk factors of severe CPP

Yu Huang et al. BMC Infect Dis. .

Abstract

Background: Chlamydia penumoniae (CP) pneumonia (CPP) in children often receives less clinical attention due to its relatively mild presentation. This study comparatively analyzed CPP and Mycoplasma pneumoniae pneumonia (MPP), and investigated risk factors for severe CPP.

Methods: A retrospective analysis was conducted on 176 CPP patients and 176 concurrently hospitalized MPP patients during the same period to compare clinical features. CPP cases were further stratified into severe and mild subgroup to identify risk factors.

Results: The number of hospitalized children with CPP increased in 2024 compared to 2023, with a significant surge observed from December 2024 to February 2025. CPP patients were significantly older than MPP patients (mean age: 10.53 ± 2.89 vs. 6.68 ± 2.88, p < 0.05) and exhibited longer durations of cough and higher rates of chest pain (p < 0.05). Laboratory findings revealed significantly elevated white blood cell (WBC) and eosinophil (EOS) counts in CPP versus MPP (p < 0.05). Severe CPP accounted for 6.8% of cases, and binary logistic regression identified eosinophil count as a potential biomarker for severe CPP (p < 0.05).

Conclusions: The number of hospitalized children with CPP increased in 2024 compared to 2023. CPP manifested more prominent cough and chest pain symptoms compared to MPP patients. EOS count levels may serve as a potential biomarker of severe CPP.

Keywords: Chlamydia pneumoniae pneumonia; Community-acquired pneumonia; Cough; Mycoplasma pneumoniae pneumonia.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: The study adheres to the statement of the Declaration of Helsinki. This study was approved by the ethics committee of the children’s hospital affiliated to Zhejiang University school of medicine and informed consent was obtained from the child’s parents. The children’s parents have informed and consented to the publication. This study does not involve any animal experiments, and ethics approval and informed consent for animals are not required. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
CPP: Chlamydia pneumoniae pneumonia, MPP: Mycoplasma pneumoniae pneumonia. Match the number on a monthly basis: Using month as a stratification variable, the number of cases randomly sampled per month in the MPP group must equal the number of admissions in the corresponding month of the CPP group. This month-matched approach ensures identical total sample sizes between the control and experimental groups. Chest imaging confirms pneumonia: Chest radiograph or chest CT indicates pneumonia (completed by our unit, or completed by another unit but recorded in the medical history). Chlamydia pathogen positive: positive for chlamydia nucleic acid in throat swab or alveolar lavage fluid, or positive for CP-specific IgM. Presence of underlying medical conditions: pulmonary tuberculosis, congenital lung anomalies, pulmonary tumors, etc
Fig. 2
Fig. 2
Distribution of hospitalization patients with Chlamydia pneumoniae (CP) pneumonia (CPP) in our center. Distribution of hospitalization durations for community-acquired pneumonia (CAP) patients with positive CP nucleic acid tests or elevated IgM levels admitted to our center from January 2023 to February 2025. This figure is original and created by the authors
See this image and copyright information in PMC

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