Objective: To probe into the etiological characteristics of pneumonia complicated with pleural effusion in hospitalized children

so as to provide pathogenic reference for rational diagnosis and treatment of children with pneumonia and pleural effusion. Methods: Medical records and sputum specimens of 361 hospitalized children with pneumonia complicated with pleural effusion admitted into Children’s Hospital of Soozhou University from 2010 to 2018 were collected. Seven kinds of common respiratory virus were detected by direct immunofluorescence. Fluorescence quantitative polymerase chain reaction (PCR) was used to detect Mycoplasma pneumoniae (MP)

Chlamydia pneumoniae (CP)

Boka virus (HBoV) and Mycobacterium tuberculosis. Rhinovirus (HRV) and human metapneumovirus (hMPV) were detected by reverse transcription-polymerase chain reaction (RT-PCR)

and the bacteria were cultured. Venous blood was collected within 24 h after admission and after treatment for 7 to 10 d. MP antibody IgG and IgM were detected by enzyme-linked immunosorbent assay (ELISA). Results: The total pathogenic detection rate of 361 children with pneumonia complicated with pleural effusion was 82.83%

of which MP detection rate was 67.59%

virus detection rate was 15.51%

bacteria detection rate was 19.39%

mixed infection rate was 20.50%

and M. tuberculosis detection rate was 2.22%. Viruses were mainly detected by hBoV and HRV

bacteria were mainly detected by Streptococcus pneumoniae (SP) and Haemophilus influenzae (HI)

and mixed infections were mainly detected by bacteria+MP and virus+MP. The virus detection rate was highest in children with pneumonia complicated with pleural effusion from 1 to 3 years

and lowest in children >6 years (P<0.05)

the MP detection rate increased gradually with the increase of age (P<0.05). The bacterial detection rate of children from 1 to 3 years and >3 to 6 years was significantly higher than that of >6 years (P<0.05)

and the mixed infection rate of children from 1 to 3 years was the highest (P<0.05). The detection rate of MP was the highest in summer and the lowest in spring (P<0.05). The detection rate of virus was relatively low in summer

while that of bacteria was relatively high in autumn and winter. Conclusion: MP is the most major pathogen of pneumonia complicated with pleural effusion

especially in the summer and autumn

followed by SP. With the age increasing

the MP detection rate is increased. And mixed infection and tuberculosis can not be ignored.