General Information: USA300, a methicillin resistant strain of Staphylococcus aureus, has been implicated in epidemiologically unassociated outbreaks of skin and soft tissue infections among healthy individuals in at least 21 U.S. states, Canada and Europe. USA300 is also noted for its strong association with unusually invasive disease, including severe septicemia, necrotizing pneumonia and necrotizing fasciitis. Causes skin infections. Staphylcocci are generally found inhabiting the skin and mucous membranes of mammals and birds. Some members of this genus can be found as human commensals and these are generally believed to have the greatest pathogenic potential in opportunistic infections. This organism is a major cause of nosocomial (hospital-acquired) and community-acquired infections. S. aureus continues to be a major cause of mortality and is responsible for a variety of infections including, boils, furuncles, styes, impetigo and other superficial skin infections in humans. Also known to cause more serious infections particularly in the chronically ill or immunocompromised. The ability to cause invasive disease is associated with persistance in the nasal cavity of a host.