Infection With Community-Onset Staphylococcus aureus and Influenza Virus in Hospitalized Children

Background: Coinfection with influenza virus and Staphylococcus aureus can cause severe illness or death, and may be increasing. During the 2006-2007 influenza season, 30% of influenza-associated pediatric deaths reported to Centers for Disease Control and Prevention had S. aureus coinfection, compared with 2% to 7% in 2004-2006. The overall occurrence, however, remains unclear. Methods: To assess the burden of coinfection with influenza and community-onset S. aureus in hospitalized children, we conducted a retrospective medical record review of all children admitted to Atlanta pediatric hospitals from October 2006 to April 2007 with laboratory-confirmed influenza or S. aureus cultured from a respiratory or sterile site within 72 hours of admission. Results: Of 65 children with influenza, 7 (11%) had influenza-S. aureus coinfection; an additional 155 had community-onset S. aureus alone. Of S. aureus isolates, 43% were methicillin-resistant. Coinfected children were more frequently admitted to the intensive care unit (71%, P = 0.05) than other children with influenza (28%) or S. aureus (36%) alone and also had a significantly higher case fatality (29%, P = 0.01; 0% influenza, 5% S. aureus). Recent skin or soft tissue infection was documented in 29% of coinfected children, compared with 2% with influenza alone (P = 0.03). Conclusions: Children with influenza-S. aureus coinfection had a higher frequency of severe outcomes than children hospitalized with influenza or S. aureus alone. Coinfection should be considered in children with severe respiratory illness during the influenza season.