Etiology investigation of acute respiratory tract infections in children.

Objective To investigate the etiology of acute respiratory tract infections(ARTI) in children under 7 years old in Suzhou.Methods Bacteria and virus were tested using sputum culture and direct immunofluoresence respectively.Human metapneumovirus(hMPV) gene fragments were detected by reverse transcription polymerase chain reaction.Antibodies against mycoplasma was detected by enzyme-linked immunosorbent assay in paired sera.Results Etiological agents were identified in 1 107 cases(66.4%) out of 1 668 patients.Viral infections were in 359 cases(21.5%),bacterial infections were in 271 cases(16.3%),and Mycoplasma pneumoniae 222 cases(13.3%),compound infections 255 cases(15.3%).Respiratory syncytial virus(RSV) was the major viral pathogen,followed by hMPV.Streptococcus pneumoniae was the prominent pathogen of bacterial pneumonia,followed by Haemophilus influenzae.Conclusion ①Viral infection is the most common cause of ARTI in children under 7 years old in Suzhou,followed by bacteria and mycoplasma.②RSV is the major cause of ARTI in infants and young children during winter and spring in Suzhou.There is no evidence of outbreak of influenza and parainfluenzae virus infection.There is a peak of hMPV infection from March to May in 2008.Streptococcus pneumoniae and Haemophilus influenzae are the prominent pathogens of bacterial pneumonia.Mycoplasma pneumoniae infection is more common in children older than 1 year old,compound infection is more often in children less than 3 years old.