To determine the prevalence and clinical features of codetected respiratory etiological agents for acute respiratory infection in hospitalized children.

Nasopharyngeal aspirates were obtained from hospitalized children with acute respiratory infection at Dankook University Hospital from September 2003 through June 2005. Immunofluorescent staining and culture were used for the detection of respiratory viruses (influenza virus [IFV] types A, B; parainfluenza virus [PIV] types 1, 2, 3; respiratory syncytial virus [RSV]; adenovirus [AdV]). Polymerase chain reaction (PCR) assays were used for Mycoplasma pneumoniae (MP) and Chlamydia trachomatis (CT) detection, and PCR and culture were performed for enterovirus detection. Acid-fast staining and culture were performed for tuberculosis detection. The demographic and clinical characteristics were reviewed retrospectively from the patients medical records.

Evidence of two or more microbes was found in 28 children: RSV was detected in 14, PIV 3 in 10, AdV in 10, MP in 8, PIV 2 in 8, CT in 4, and PIV 1 in 3. Codetected agents were found as follows: RSV+PIV 2, 6 patients; AdV+MP, 4 patients; AdV+PIV, 3 patients; RSV+MP, 3 patients; PIV 1+PIV 3, 3 patients. Distinct peaks of codetected agents were found in epidemics of MP and each respiratory virus.

The codetected infectious agents were RSV, PIV, AdV, and MP, with distinct peaks found in epidemics of MP and each respiratory virus. Although advances in diagnostic methods have increased the prevalence of codetection, its clinical significance should be interpreted cautiously.