Abstract: Objective The Objective of this research is to analyze the IgM antibody test of 9 respiratory pathogens causing child respiratory tract infections,in the selected tertiary hospital to provide guidance for the clinical treatment of these infections. Methods This research the indirect immune-fluorescence technique was used to detect IgM against 9 respiratory tract infection pathogens in the serums of 4 391 outpatient and inpatient child respiratory infection cases,including mycoplasma pneumonia （MP）,syncytial virus （RSV）,Chlamydia pneumonia （Cpn）,Coxiella Burnetii （COX）,Influenza B Virus （IFVB）,Legionella pneumophila （LP1）,adenovirus（ADV）,influenza A virus （IFVA）,and parainfluenza virus （PIVs）. These pathogens were studied for the distributions of their detections from serums taken from different gender,different age groups,and different seasons,and their co-infections. Results 1 564 cases among all the 4,391 cases of child respiratory infections were tested positive,positive rate is 35.62%. The positive rate for males and females were 31.73% and 40.83% respectively. The difference is statistically significant （P<0.05）. The top three pathogens causing child respiratory tract infections were MP （1 449 cases,33.00%）,PIVs （348 cases,7.93%）,IFVB （87 cases,1.98%）. The primary co-infection was the co-infection of MP and PIVs,accounting for 56.01% of all infections. The positive rate was highest in the 1-3 year-old age group （P<0.05%） and highest in autumn （P<0.05）. Conclusion The primary pathogens causing child respiratory tract infection in the selected tertiary hospital were MP,PIVs,and IFVB. There were statistically significant differences in the detection rate of these pathogens among different age groups and in different seasons. Clinical treatments thus should be customized for child patients with respiratory tract infections basing upon their pathogen test results so as to optimize the use of anti-bacterial drugs,and avoid multiple infections.

Key words: Respiratory infection, Indirect immunofluorescence, IgM antibodies