Association of 2009 Pandemic Influenza A (H1N1) Infection and Increased Hospitalization With Parapneumonic Empyema in Children in Utah

Division of Pediatric Infectious Diseases, Department of Pediatrics, University of Utah Health Sciences Center, Salt Lake City, UT, USA.
The Pediatric Infectious Disease Journal (Impact Factor: 2.72). 10/2010; 29(10):905-9. DOI: 10.1097/INF.0b013e3181df2c70
Source: PubMed


During previous influenza pandemics, many deaths were associated with secondary bacterial infection. In April 2009, a previously unknown 2009 influenza A virus (2009 H1N1) emerged, causing a global influenza pandemic. We examined the relationship between circulating 2009 H1N1 and the occurrence of secondary bacterial parapneumonic empyema in children.
Children hospitalized with parapneumonic empyema from August 2004 to July 2009, including a period when the 2009 H1N1 circulated in Utah, were identified using International Classification of Diseases, Ninth Revision codes. We compared the average number of children diagnosed with influenza A and the number of admissions for empyema per month for the previous 4 seasons to rates of empyema during the 2009 H1N1 outbreak. We identified causative bacteria using culture and polymerase chain reaction (PCR).
We observed an increase in hospitalization of children with pneumonia complicated by empyema during a severe outbreak of 2009 H1N1 during the spring and summer of 2009, compared with historical data for the previous 4 seasons. Streptococcus pneumoniae and Streptococcus pyogenes were the predominant bacteria identified.
Similar to previous pandemics, secondary bacterial infection with S. pneumoniae and S. pyogenes were associated with the 2009 H1N1 outbreak. There is an urgent need to better understand bacterial complications of pandemic influenza. In the interim, influenza vaccines, antiviral agents, and pneumococcal vaccines should be used to prevent cases of secondary bacterial pneumonia whenever possible.

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    • "The most important RTI with respect to healthcare burden is pneumonia which is associated with hospitalisation and poorer outcomes. The incidence of pneumonia is high in children admitted to hospital with more severe influenza; in 2,992 hospitalised children and adolescents with seasonal influenza, radiographic evidence of pneumonia was found in 1,072 (36 %) [30], and recently published studies in European and Asian children suggest a similar rate in hospitalised children with H1N1pdm09 influenza, with estimates ranging from 22 to 43 % [11, 69, 91, 111], although two groups found the rate to be higher for H1N1pdm09 infections during 2009 than for influenza A infections in previous seasons [5, 78]. Pneumonia is less common outside the hospital setting: in the Finnish prospective cohort study in outpatients mentioned above, pneumonia was diagnosed in 9 of 370 (2.4 %) children with confirmed influenza, 8 of whom were aged ≤6 years [51]. "
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