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Every year, influenza prevention, treatment, and complications pose challenges to pediatricians. This year, new concerns about antiviral drug resistance and complications secondary to bacterial superinfection have emerged.
The CDC recently published the results of a survey of 730 primary care physicians in Connecticut, Minnesota, New Mexico, and New York about influenza testing and antiviral prescribing practices during the 2006–2007 flu season. Most physicians (69%) used influenza testing during the flu season; of those, 88% ordered rapid antigen tests. Although more than 90% of practitioners prescribed the neuraminidase inhibitors oseltamivir and zanamivir, 26% still prescribed amantadine or rimantadine, even though these agents have not been recommended since January 2006 because they are associated with high viral-resistance rates.
The New York Times and the Associated Press reported that 3.8% of influenza virus isolates in the U.S. have a mutation that confers resistance to oseltamivir. Other countries reporting resistant strains were Norway, Denmark, France, and Britain. The CDC still recommends the use of oseltamivir at this time.
The CDC recently issued a health advisory to request that all pediatric influenza deaths be reported through local or state health departments. The advisory is also intended to heighten awareness about pediatric influenza complicated by methicillin-resistant Staphylococcus aureus (MRSA) superinfection. During the past three influenza seasons, the number of reported pediatric deaths from influenza, as well as the number of pediatric deaths with bacterial coinfection, increased. In the 2006–2007 season, 15 of 22 children with S. aureus superinfection had MRSA infection.
Centers for Disease Control and Prevention (CDC). Influenza-testing and antiviral-agent prescribing practices — Connecticut, Minnesota, New Mexico, and New York, 2006–07 influenza season. MMWR Morb Mortal Wkly Rep 2008 Jan 25; 57:61.
Altman LK. Mutant flu virus is found that resists popular drug. The New York Times. 2008 Jan 31. (http://www.nytimes.com/2008/01/31/health/31flu.html?_r=1&oref=slogin)
Centers for Disease Control and Prevention (CDC). Influenza-associated pediatric mortality and Staphylococcus aureus co-infection. 2008 Jan 30. (http://www2a.cdc.gov/HAN/ArchiveSys/ViewMsgV.asp?AlertNum=00268)
Comment
In this ever-changing environment, we need to remember that amantadine and rimantadine are no longer useful for treating influenza. The findings about oseltamivir resistance are worrisome, but, at this point, oseltamivir remains one of our best treatment options. During flu season, children with bacterial superinfection, particularly severe pneumonia, should be assessed for MRSA and treated accordingly. The increasing resistance to antiviral therapy affirms that immunization remains our best option.