MRSA  Health Article

Definition

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterial infection that is highly resistant to some antibiotics.

Alternative Names

Methicillin-resistant Staphylococcus aureus; Community-acquired MRSA (CA-MRSA); Hospital-acquired MRSA (HA-MRSA)

Causes, incidence, and risk factors

MRSA is a strain of Staphylococcus aureus (S. aureus) bacteria. S. aureus is a common type of bacteria that normally live on the skin and sometimes in the nasal passages of healthy people. MRSA refers to S. aureus strains that do not respond to some of the antibiotics used to treat staph infections.

The bacteria can cause infection when they enter the body through a cut, sore, catheter, or breathing tube. The infection can be minor and local (for example, a pimple), or more serious (involving the heart, lung, blood, or bone).

Serious staph infections are more common in people with weak immune systems. This includes patients in hospitals and long-term care facilities and those receiving kidney dialysis.

MRSA infections are grouped into two types:

• Healthcare-associated MRSA (HA-MRSA) infections occur in people who are or have recently been in a hospital or other health-care facility. Those who have been hospitalized or had surgery within the past year are at increased risk. MRSA bacteria are responsible for a large percentage of hospital-acquired staph infections.
• Community-associated MRSA (CA-MRSA) infections occur in otherwise healthy people who have not recently been in the hospital. The infections have occurred among athletes who share equipment or personal items (such as towels or razors) and children in daycare facilities. Members of the military and those who get tattoos are also at risk. The number of CA-MRSA cases is increasing.