Publication date: Jun 26, 2025

Mycoplasma pneumoniae is a common bacterial cause of respiratory infection and a leading cause of childhood community-acquired pneumonia (CAP). Increases in M. pneumoniae infection occur every 3-5 years. In the United States, M. pneumoniae prevalence decreased during and immediately after the COVID-19 pandemic. Information from 42 U. S. children’s hospitals that provided information to the Pediatric Health Information System, a database of clinical and resource use information, was used to identify discharge diagnostic codes for 2018-2024 indicating M. pneumoniae infection. M. pneumoniae-associated CAP incidence among children aged ≤18 years was significantly higher in 2024 (12. 5 per 1,000 hospitalizations) than during 2018-2023 (2. 1). During the study period, an M. pneumoniae diagnostic code was listed in 11. 5% of pediatric CAP hospitalizations, peaking at 53. 8% in July 2024. Among pediatric M. pneumoniae CAP cases, the highest percentage occurred among children aged 6-12 years (42. 6%), followed by children aged 2-5 years (25. 7%) and 13-18 years (21. 1%). The lowest occurred among those aged 12-23 months (6. 4%) and 0-11 months (4. 2%). M. pneumoniae infections in 2024 were not more severe than 2018-2023 infections, as assessed by length of hospitalization and percentage of patients admitted to an intensive care unit. The increase in M. pneumoniae infections in the United States in 2024 might be higher than previous periodic increases because the susceptible population was larger after sustained low incidence during and immediately after the COVID-19 pandemic. Health care providers should be aware of the periodicity of M. pneumoniae CAP and consider testing for this pathogen as a cause of respiratory illness among children of all ages.

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