A methicillin-resistant Staphylococcus aureus (MRSA) infection is a bacterial infection caused by the bacterium Staphylococcus aureus. The bacteria can affect the skin, blood, bones, or lungs. A person can either be infected or colonized with MRSA. When a person is infected, the bacteria cause symptoms. A person colonized also has the bacteria, but it may not cause any symptoms. An MRSA infection is serious because the bacteria are resistant to many antibiotics that are used to treat infections.

There are two types of MRSA infection: community-acquired and nosocomial. People who have a community-acquired MRSA infection were infected outside of a hospital setting (for example, a dormitory). Nosocomial MRSA infections occur in healthcare settings (such as hospitals or clinics).

An MRSA infection can spread several ways:

  • Contaminated surfaces
  • Person-to-person
  • From one area of the body to another