OBJECTIVETo study the distribution of pathogenic microorganisms in different genders, age groups and seasons in children with community-acquired pneumonia (CAP) and the relationship between the distribution of pathogenic microorganisms and clinical features.

METHODSA total of 1,155 children with CAP were enrolled, among whom there were 670 boys and 485 girls, with a mean age of 3.1±2.8 years (range: one month to 14 years). Indirect immunofluorescence assay, particle agglutination test, enzyme-linked immunosorbent assay, colloidal gold method. and bacterial culture were applied to determine common respiratory pathogenic microorganisms in sputum, throat swabs, blood samples, bronchoalveolar lavage fluid, and urine.

RESULTSA total of 758 specimens (65.63%) were tested positive by pathogen detection. The top three dominant pathogens were Mycoplasma pneumoniae (MP, 43.64%), bacteria (15.12%), and respiratory syncytial virus (RSV, 9.26%), and the rate of mixed infection was 16.02%. The rates of MP infection between boys and girls with CAP were different (40.8% vs 47.6%; P<0.05). The MP detection rate was the highest in the age group of 6-14 years (77.4%) and the lowest in children younger than 1 year (11.2%), while the detection rates of bacteria and RSV were the highest in children younger than 1 year (21.2% and 17.2%, respectively). The MP detection rate was significantly higher in summer and autumn than in winter and spring, while the detection rates of bacteria and RSV in summer and autumn were significantly lower than those in winter and spring. Among children who were MP positive, fever, chills, cough, crackles were more likely to appear; children with RSV infection were more likely to have wheezes; children with bacterial infection were less likely to have cough. Serum levels of C-reactive protein and procalcitonin were associated with bacterial infection (OR=1.747 and 1.418, respectively; both P<0.05).

CONCLUSIONSMP plays a more and more important role in the pathogenic microorganisms of CAP in children. Prevalence and outbreaks of MP infection among children should be alerted in summer and autumn. There are differences in the detection rate of various pathogenic microorganisms in CAP children with various age groups. The clinical features of children with CAP caused by different pathogenic microorganisms are different.