Secondary bacterial infections with H1N1

Physicians should be on the alert for secondary bacterial infections in children with H1N1. An increase in the rate of hospitalization of children with pneumonia complicated by empyema was observed during a severe outbreak of H1N1 in 2009, noted researchers, who reported their findings in the Pediatric Infectious Disease Journal.

Researchers identified 21 cases of children younger than 18 years old who were admitted to Primary Children's Medical Center in Salt Lake City, Utah, with a confirmed parapneumonic empyema from May 1, 2009, to July 31, 2009. These cases were significantly greater (P<.001) than the historical average of 10.8 cases during the same period in the years 2004 to 2008. Twelve cases of empyema occurred during the peak period of H1N1 in June 2009 versus a historical rate of 3.5 cases per month in June (P<.001).

Children with empyema were younger than those without empyema (median age, 37 months vs 47 months), and their hospital stays were longer (median length of stay, 7 days vs 3 days). All children hospitalized for pneumonia with empyema had a history of an influenza-like illness a median of 8 days before being diagnosed with empyema.

Although a temporal association between H1N1 and empyema does not prove causality, the increase in empyema may represent bacterial pneumonia complicating 2009 H1N1 infection, according to the researchers.

The researchers recommend that children with signs of influenza be treated "promptly and empirically" with antiviral medications and be up-to-date on their pneumococcal conjugate vaccine, and for those children older than 2 years who have high-risk medical conditions, pneumococcal polysaccharide vaccine.

Ampofo K, Herbener A, Blaschke AJ, et al. Association of 2009 pandemic influenza A (H1N1) infection and increased hospitalization with parapneumonic empyema in children in Utah. Pediatr Infect Dis J. 2010;29(10):905-909.