To investigate the distribution characteristics of pathogens causing community-acquired pneumonia (CAP) in children in Zunyi region from 2020 to 2024, and to analyze their variations by year, age and season, in order to provide evidence for empirical anti-infection therapy.

Clinical data of hospitalized children with bacterial CAP from five hospitals in Zunyi were collected, retrospectively. Total of 21 546 cases with positive sputum cultures and meeting CAP diagnostic criteria were included. The pathogen spectrum and its distribution across different years, age groups and seasons were analyzed. The characteristics of pathogen composition across different ages and seasons were analyzed by Pearson Chi-square test, and the pathogen distribution across different years was analyzed by Chi-square trend test.

Total of 21 546 children with CAP who had positive sputum cultures were enrolled, including 13 307 males (61.8%) and 8 239 females (38.2%). There were statistically significant differences in the distribution of children among different years, seasons and age groups (χ²=1 103.4, 1 083.9, 3 733.9; all P<0.001). The detection rates of Gram-negative bacteria and Gram-positive bacteria showed significant differences in distribution among different years (χ²=189.5, P<0.001), and the detection rate of Gram-negative bacteria (53.0%) exceeded that of Gram-positive bacteria (47.0%) in 2024. The top 5 pathogens in terms of detection rate were Haemophilus influenzae (6 972 cases, 32.4%), Streptococcus pneumoniae (5 746 cases, 26.7%), Staphylococcus aureus (3 825 cases, 17.8%), methicillin-resistant Staphylococcus aureus (MRSA) (2 027 cases, 9.4%) and Escherichia coli (852 cases, 4.0%). Age distribution: children in infant group were mainly infected with Haemophilus influenzae (3 344/11 073, 30.2%), Staphylococcus aureus (2 702/11 073, 24.4%) and Escherichia coli (742/11 073, 6.5%); children in the toddler and preschool group were mainly infected with Streptococcus pneumoniae [37.9% (2 228/5 879) and 33.1% (1 217/3 672)] and Haemophilus influenzae [39.3% (2 308/5 879) and 31.2% (1 145/3 672)]; children in the school-age group had the highest detection rate of MRSA (348/922, 37.7%). Seasonal distribution: the bacterial infection rate was higher in autumn and winter. Haemophilus influenzae and Streptococcus pneumoniae were the main pathogens in all four seasons, among which Haemophilus influenzae had the highest detection rate in winter (2 627/6 238, 42.1%) and Streptococcus pneumoniae had the highest proportion in autumn (1 821/5 435, 33.4%). Drug resistance analysis showed that Haemophilus influenzae was highly resistant to trimethoprim-sulfamethoxazole, ampicillin and cefuroxime [resistance rates were 95.3% (6 644/6 972), 89.6% (6 247/6 972) and 73.4% (5 142/6 972)]. The resistance rates of Escherichia coli to ampicillin, cefuroxime and ceftriaxone were 91.1% (752/825), 83.0% (685/825) and 78.4% (647/825), respectively, and Escherichia coli was sensitive to piperacillin/tazobactam and meropenem; The resistance rate of Streptococcus pneumoniae to tetracycline was 100% (5 746/5 746), while the resistance rate of Staphylococcus aureus to penicillin was 92% (3 519/3 825), and the resistance rate of MRSA to clindamycin and erythromycinhad were both higher than 90%, and all the above Gram-positive bacteria were sensitive to vancomycin, linezolid, etc.

There were significant differences in the detection rates of pathogens from children with CAP in Zunyi region among different years, seasons and age groups. In 2024, the detection rate of Gram-negative bacteria exceeded that of Gram-positive bacteria. The dominant pathogenic bacteria varied among different age groups, and the infection rates were higher in autumn and winter. Common pathogenic bacteria were highly resistant to various conventional antibiotics. It is necessary to select reasonable antibiotics according to the drug sensitivity test results.