To investigate the etiological distribution of severe pneumonia in children of Ji'nan, to provide evidence for the formulation of clinical treatment for this disease.

A retrospective analysis was performed on a total of 551 hospitalized pediatric patients with severe pneumonia in Ji'nan Children's Hospital from January 2018 to December 2019. All the clinical and etiologic records were collected and analyzed.

A total of 551 children with severe pneumonia were included in this study, including 388 boys and 163 girls, and the ratio of males to females was 2.4∶1. The age ranged from 1 month to 12 years. The positive rate of pathogenic bacteria was 50.2% (276/551), and the numbers of cases of bacterial infection, viral infection, mycoplasma pneumoniae infection, chlamydia pneumoniae infection, and mixed infection were 62 (11.3%), 92 (16.7%), 29 (5.3%), 4 (0.7%), and 89 (16.2%), respectively. A total of 210 children aged ＜3 months were included, of whom 85 cases (40.5%) were positive, and virus was the main pathogen detected (17.1%). A total of 302 children aged 3 months to ＜5 years were included, of whom 155 cases (51.3%) were positive, and most of them were infected with virus (17.5%). A total of 39 children aged 5-15 years were included, of whom 36 cases (92.3%) were positive, and mixed infection was the main cause (56.4%). Among viral infections, adenovirus infection took the first place, with 36 cases (39.1%) detected. The detection rate of Gram-negative bacilli was the highest among bacterial infections, with 48 cases (77.4%) detected. In spring, summer, autumn, and winter, the positive detection rates of virus infection were 25.0%, 7.6%, 21.7%, and 45.7%, the positive detection rates of bacterial infection were 16.1%, 9.7%, 35.5%, and 38.7%, and the positive detection rates of mixed infection were 19.1%, 13.5%, 20.2%, and 47.2%, respectively.

Severe pneumonia in children in Ji'nan is mainly caused by viral infection, with adenovirus infection taking the first place. Gram-negative bacillus infection is the main bacterial infection. Viral infection is the main pathogen of severe pneumonia in children under 5 years old, and mixed infection is the main pathogen in children over 5 years old. Bacterial infections and mixed infections are more common in autumn and winter, and viral infections are more common in winter and spring.