Influenza A viruses—including the 2 subtypes 2009 (H1N1) and A (H3N2)—and influenza B viruses are currently circulating worldwide. The pandemic H1N1 is becoming the predominant strain in both hemispheres with an increased activity in the Southeast Asia (Nicogossian et al. 2010). 

It is estimated that worldwide, influenza viruses are responsible for infecting 1 billion individuals annually, resulting in 300,000 to 500,000 deaths. The economic burden in the US alone is a staggering US $1 to 3 billion, annually attributed to related absenteeism, secondary respiratory bacterial infections, hospitalizations, and use of scarce and costly medical resources. 

Primary protective measures consist of a combination of vaccinations, environmental and physical hygiene practices, and, in appropriate settings, the use of antiviral drugs to either prevent or shorten the course of the infection. Recently, however, resistance to antiviral drugs was reported (Glickman et al. 2010; Memoli et al. 2010; Bright et al. 2006; Gooskens et al. 2009). 

In the United States, the CDC has issued interim recommendations and updates for the prevention of the development of resistance to antiviral medications (Centers for Disease Control and Prevention 2009; Centers for Disease Control and Prevention 2010). Recently, influenza has been implicated as a contributing factor in the development of AMDR and fatal MRSA pneumonia (Creel et al. 2009; Pedal and Nolte 2010)