Incidence of bacterial coinfection with respiratory syncytial virus bronchopulmonary infection in pediatric inpatients

Bacterial coinfection occurs in pediatric bronchopulmonary infections caused by respiratory syncytial virus (RSV), but the incidence is uncertain. Our subjects are 188 pediatric inpatients having RSV bronchopulmonary infection in two hospitals in Chiba Prefecture between 2005 and 2007. On admission, antigen detection kits using nasopharyngeal aspirate were performed to detect RSV infection and washed sputum bacterial culture was performed to detect bacterial infection. Of the 188 pediatric inpatients with RSV bronchopulmonary infection, 95 (50.5%) patients were aged less than 1 year, 57 (30.3%) were aged 1-2 years, and 36 (19.1%) were aged 2 years or more. Thirty-six (19.1%) patients were associated with bronchial asthma attacks. Pathogenic bacteria were predominantly isolated from 43.6% of the patients. The three most frequently isolated bacteria were Haemophilus influenzae (43.9%), Streptococcus pneumoniae (36.6%), and Moraxella catarrhalis (29.3%). We found that 38.9% of H. influenzae strains were beta-lactamase-nonproducing ampicillin-resistant strains. All S. pneumoniae strains were penicillin G (PcG) sensitive. However, 21.9% of S. pneumoniae strains showed PcG minimum inhibitory concentration values of 2 mu g/ml. RSV bronchopulmonary infections in hospitalized children are often associated with antimicrobial-resistant bacterial infection in their lower airways. These results indicate that we should be aware of bacterial coinfections in the management of pediatric inpatients with RSV bronchopulmonary infection.