Polymicrobial Acute Respiratory Infections in a Hospital-based Pediatric Population

Background: The clinical impact of polymicrobial respiratory infections remains uncertain. Previous reports are contradictory regarding an association with severe disease. Methods: Three hundred forty-six specimens from children with acute respiratory illness identified at the University of Iowa Hospitals and Clinics Clinical Microbiology Laboratory were evaluated by direct immunofluorescent assay and/or viral culture by Clinical Microbiology Laboratory and later by molecular study for the presence of influenza, parainfluenza, respiratory syncytial virus, adenovirus, human metapneumovirus, rhinovirus and human bocavirus. Demographic and clinical data were abstracted from medical records. Results: Multiple viruses were detected in 46 (21.7%) of 212 virus-positive specimens with the most frequent virus-virus combinations being HRV-respiratory syncytial virus (n = 12), HRV-human bocavirus (n = 6) and HRV-parainfluenza virus 3 (n = 4). Risk factors for coinfection included male gender (OR [odds ratio]: 1.70, 95% confidence interval [CI]: 0.83-3.46), 6 months to 1 year age (OR: 2.15, 95% CI: 0.75-6.19) and history of immunosuppression (OR: 2.05, 95% CI: 0.99-4.23). Children with viral coinfections were less likely than children with single virus infections to be admitted to an intensive care unit (OR: 0.32, 95% CI: 0.08-1.27); however, this may be explained by undetected viral-bacterial coinfections. Conclusions: HRV, respiratory syncytial virus, human bocavirus, and polymicrobial infections were prevalent in this study. Although the cross-sectional design could not easily examine polymicrobial infection and disease severity, prospective, population-based research regarding the clinical impact of such infections is warranted.