Objective  To analyze the distribution characteristics and drug resistance of bacterial pathogens in children with community-acquired pneumonia (CAP) in a single center, and to provide evidence for clinical diagnosis and treatment.

Methods  A total of 2850 children with CAP admitted to the Department of Pediatrics of a tertiary hospital in Sichuan between January 2022 and December 2024 were enrolled. Clinical data, sputum culture and bacterial drug sensitivity results, and respiratory pathogen nucleic acid testing results were collected. A retrospective analysis was conducted on the clinical data, etiological testing results, and drug sensitivity data.

Results  Among the 2850 CAP children, the overall pathogen positivity rate was 73.4% (2093/2850), with viral, bacterial, and Mycoplasma pneumoniae/Chlamydia pneumoniae infections accounting for 33.6% (958/2850), 32.6% (929/2850), and 24.7% (703/2850), respectively. The predominant bacterial pathogens identified were Haemophilus influenzae (38.8%), Streptococcus pneumoniae (29.7%), Moraxella catarrhalis (21.4%), and Staphylococcus aureus (10.1%). Multivariable logistic regression analysis (Bonferroni-corrected) revealed that age was an independent risk factor for bacterial infection, although the risk profile varied by bacterial species. The risk of Staphylococcus aureus infection was highest during infancy (infancy adjusted odds ratio aOR = 1) and was significantly lower among the school-age children (aOR = 0.09, 95% CI: 0.02-0.52). The risk of Streptococcus pneumoniae infection peaked in the preschool children (aOR = 2.66, 95% CI: 1.75-4.05), followed by school-age children (aOR = 2.60, 95% CI: 1.48-4.57) and toddlers (aOR = 1.90, 95% CI: 1.26-2.87). The risk of Moraxella catarrhalis infection significantly decreased in school-age children (aOR = 0.24, 95% CI: 0.08-0.69). Antimicrobial susceptibility testing demonstrated that the resistance rates of Haemophilus influenzae and Moraxella catarrhalis to ampicillin were 75.45% and 41.53%, respectively. The resistance rate of Streptococcus pneumoniae to erythromycin was 93.75%, while that of Staphylococcus aureus to penicillin was 83.33%.

Conclusion  In this pediatric CAP cohort, the main bacterial pathogens are Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis, and Staphylococcus aureus. The distribution of bacterial pathogens exhibits distinct age-specific characteristics.