Influenza A viruses cause recurrent, seasonal epidemics and occasional global pandemics with devastating levels of morbidity and mortality. The ability of influenza A viruses to adapt to various hosts and undergo reassortment events ensures constant generation of new strains with unpredictable degrees of pathogenicity, transmissibility, and pandemic potential. Currently, the combination of factors that drives the emergence of pandemic influenza is unclear, making it impossible to foresee the details of a future outbreak.

Identification and characterization of influenza A virus virulence determinants may provide insight into genotypic signatures of pathogenicity as well as a more thorough understanding of the factors that give rise to pandemics.

Widespread use of antibiotics in hospitalized patients contributes to the development of multidrug resistant organisms that make many infections increasingly difficult to treat. Despite calls to prescribe antibiotics judiciously, many physicians continue to order antibiotics for inpatients who do not need them.

This Issue Brief investigates antibiotic use in hospitalized adults with a confirmed viral infection, a group of patients that may not benefit from such therapy. Understanding the factors that lead to inappropriate antibiotic use may help change clinical practice and limit antibiotic resistance.