Community-acquired Pneumonia Due to Chlamydia Pneumoniae

This international retrospective Franco-Swiss study focuses on community-acquired pneumonia (CAP) caused by Chlamydia pneumoniae. The working hypothesis is that the prevalence of C. pneumoniae pneumonia is overestimated by the medical community. The primary objective is to determine the true prevalence of C. pneumoniae infections among patients with pneumonia who underwent simplex or multiplex PCR testing. Secondary objectives include; 1. Outpatient management 2. Hospitalization in a medical ward 3. Admission to the intensive care unit 4. In-hospital mortality 5. Radiological presentation of patients with community-acquired pneumonia (CAP) caused by Chlamydia pneumoniae 6. Prevalence of viral or bacterial co-infections associated with C. pneumoniae CAP

Inclusion Criteria: * Positive simplex or multiplex PCR for Chlamydia pneumoniae on an upper or lower respiratory tract specimen between January 2015 and December 2025. * Availability of clinical data allowing confirmation of pneumonia diagnosis. Exclusion Criteria: * Patient opposition to the use of medical data for research purposes. * Absence of pneumonia diagnosis. * Insufficient clinical data for analysis.