MRSA is a resistant form of the bacteria Staphylococcus aureus (Methicillin-resistant Staphylococcus aureus). Patients with MRSA may or may not be symptomatic and may or may not need hospitalization. Some patients with MRSA are merely carriers and display no symptoms of illness and may not require treatment at all. However, if left untreated, certain MRSA infections may evolve into symptomatic infections and subsequently into sepsis, which may further progress to septic shock. Septic shock, the most severe form of sepsis, is lethal in up to 40% of cases.

Sepsis, by definition, is always symptomatic, and almost without exception requires medical treatment and hospitalization to cure. Sepsis occurs when an individual develops a localized infection in one part of the body which causes a systemic response in the body. People who have had recent surgery or who are currently fighting infection are at risk of sepsis.

Both of these conditions have a higher rate of occurrence in hospitalized patients. Hospital personnel traveling room to room interact with multiple ill patients every day and may serve as vectors for the spreading of these infections. Infection control efforts, including meticulous hand washing efforts and sterile cleaning of rooms at regular intervals, have decreased these occurrence rates.