Objective To analyze the changing epidemiological characteristics of Mycoplasma pneumoniae (MP) infection among hospitalized children with respiratory tract infections in Suzhou from January 2022 to December 2024, providing evidence for clinical management and public health interventions.

Methods A retrospective study was conducted on 35712 children hospitalized with respiratory infections in the Department of Internal Medicine at Soochow University Affiliated Children’s Hospital. The MP nucleic acid in throat swab specimens was detected by real-time fluorescence quantitative PCR combined with capillary electrophoresis. MP positivity rates were compared across years, sex, age groups (0–＜1, 1–＜3, 3–6, >6 years), months, and infection types (single MP infection vs. co-infection).

Results Among 9406 MP-positive cases (26.34% positivity rate), single MP infections accounted for 61.85% (5816/9406) and co-infections for 38.15% (3590/9406). Annual positivity rates differed significantly (χ² = 1909.237, P<0.001): 10.37% (732/7062) in 2022, 37.80% (5125/13557) in 2023, and 23.51% (3549/15093) in 2024. Females had a higher positivity rate (27.17%, 4259/15674) than males (25.69%, 5147/20038; χ²=10.012, P=0.002), peaking in females in 2023 (38.19%). Positivity increased significantly with age (χ²=2425.512, P < 0.001): 12.51% (0–<1 year), 16.76% (1–<3 years), 26.08% (3–6 years), and 41.81% (>6 years). The >6years group reached 49.05% positivity in 2023. Monthly variations were significant (χ² = 892.329, P < 0.001), with shifting seasonal peaks. The pattern of epidemic peaks has changed markedly: in 2022, only December exceeded 20.00% (22.28%); in 2023, high incidence persisted in January and from May to December (21.15%–54.04%); in 2024, high incidence occurred in January and from April to September (22.62%–34.87%). Regardless of single or mixed infection, the positivity rate in 2023 was higher than in other years (P<0.001). Among mixed infections, MP co-infection with human rhinovirus was the most common (59.97%).

Conclusion The overall MP positivity rate was 26.34% during 2022–2024, with an anomalous peak in 2023. Epidemiological shifts include: higher positivity in older children (>6 years), slightly higher rates in females, the seasonal epidemic pattern changed significantly, shifting from a single winter peak in 2022 to a prolonged period from spring–summer (starting in May) to winter in 2023–2024, with the summer peak in 2023 being particularly prominent. These findings underscore the need for enhanced school-based MP infection control, particularly during summer-autumn periods.