The impact of dual viral infection in infants admitted to a pediatric intensive care unit associated with severe bronchiolitis

Introduction: Bronchiolitis is a major cause of morbidity and mortality in early childhood worldwide. The presence of more than one pathogen may influence the natural history of acute bronchiolitis in infants. Objective: To investigate the relevance of dual viral infection in infants with severe bronchiolitis hospitalized in a short-term unit compared with those in a pediatric intensive care unit (PICU). Study Design: One hundred eighty infants < 1 year old hospitalized with bronchiolitis in a short-term unit (n = 92) or admitted to the PICU (n = 88) during 2 consecutive winter seasons 2003/2004 and 2004/2005 were evaluated. Molecular biology and standard methods were used to diagnose human respiratory viruses in nasal/throat swabs and nasal aspirates. Clinical data related to host factors and viral prevalence were compared among infants requiring or not PICU support. Results: A viral agent was identified in 96.1% of infants with bronchiolitis. Respiratory syncytial virus (70.6% and 73.6%, respectively in the short-term unit and PICU) and rhinovirus (18.5% and 25.3%, respectively in the short-term unit and PICU) were the main detected respiratory viruses in infants hospitalized in both units. No significant difference in viral prevalence was observed between the populations studied. From multivariate analysis, infants with coinfections were 2.7 times (95% CI: 1.2-6.2) more at risk for PICU admission than those with a single infection. Respiratory syncytial virus and rhinovirus were the viruses most frequently identified in mixed infections in infants hospitalized with bronchiolitis. Conclusions: Dual viral infection is a relevant risk factor for the admission of infants with severe bronchiolitis to the PICU.