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Researchers note 5-fold increase in S. aureus coinfection with pediatric influenza in 3 years

Wednesday, October 29 2008 | Comments

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What's This? Pediatricians should be concerned with low influenza vaccination rates among children and aware of a significant increase in pediatric influenza deaths associated with Staphylococcus aureus coinfection, suggests a study of pediatric influenza-associated mortality in the United States.

Researchers with the Centers for Disease Control and Prevention reviewed data from case reports submitted to the center's influenza surveillance program, which since October 2004 has required reporting of influenza-associated pediatric mortality. An influenza-associated pediatric death is defined as a death in a child younger than 18 years of age who has a clinically compatible illness and laboratory-confirmed influenza.

From Oct. 1, 2004 to Sept. 30, 2007, clinicians reported 166 pediatric influenza-associated deaths. In the first 2 seasons, pediatric influenza-associated deaths were approximately equal (n=47 and n=46 for the 2004-2005 and 2005-2006 seasons, respectively). In the 2006-2007 influenza season, the number of deaths increased to 73.

Reports of bacterial coinfection increased substantially from the 2004-2005 to the 2006-2007 influenza season (6%, 15%, and 34% for the 3 seasons, respectively). S. aureus was isolated in 1 case in 2004-2005, 3 cases in 2005-2006, and 22 cases in 2006-2007. Of these, 64% were methicillin-resistant S. aureus (MRSA). The researchers observed that children with bacterial coinfection were significantly older and more likely to have pneumonia and acute respiratory distress syndrome than those children who were not coinfected.

Of 90 children who were recommended for influenza vaccination, only 5 (6%) were fully vaccinated.

Noting that bacterial pneumonia is thought to have been a major cause of increased mortality during influenza pandemics, the investigators stressed the importance of future research to identify risk factors for influenza bacterial coinfection and to determine the impact of influenza vaccination and antiviral agents in preventing pediatric mortality.

The investigators also noted steps that physicians should take pending additional research, including testing for influenza in children with moderate to severe respiratory illness. If infected, these children should be treated with oseltamivir or zanamivir. In addition, physicians should consider treating a child with suspected S. aureus pneumonia during influenza season with vancomycin or other antibiotic to treat MRSA if the child resides in an area where MRSA is prevalent or if the child has risk factors for MRSA infection (eg, underlying medical conditions or history of MRSA infection or colonization).

"Increasing rates of MRSA nasal carriage may increase the potential for coinfection with MRSA and influenza virus, resulting in severe morbidity and mortality in children, " the authors concluded. (Finelli L, et al. Pediatrics 2008;122:805-811.)

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