Methicillin-resistant Staphylococcus aureus; Community-acquired MRSA (CA-MRSA); Hospital-acquired MRSA (HA-MRSA)
Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterial infection that is highly resistant to some antibiotics.
MRSA is caused by a strain of Staphylococcus aureus (S. aureus) bacteria. S. aureus is a common type of bacteria that normally lives on the skin and sometimes in the nasal passages. MRSA refers to S. aureus strains that do not respond to the antibiotics normally used to cure 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, 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:
Staph skin infections cause a red, swollen, and painful area on the skin. Other symptoms may include:
Symptoms of a more serious staph infection may include:
Depending on your symptoms, your doctor may recommend the following tests to detect and confirm the bacteria causing the infection:
Draining the skin sore is often the only treatment needed for a local skin MRSA infection. This can be done at the doctor's office.
More serious MRSA infections, especially HA-MRSA infections, are becoming increasingly difficult to treat. Antibiotics that may still work include:
It is important to finish all doses of antibiotics you have been given, even if you feel better before the final dose. Unfinished doses can lead to further drug resistance in the bacteria, or can cause an infection that seemed to be cured to return.
Other treatments may be needed for more serious infections. The person will be admitted to a hospital. Treatment may involve:
For more information about MRSA, see the Centers for Disease Control web site:
How well a person does depends on the severity of the infection and their overall health. MRSA-related pneumonia and blood poisoning are associated with high death rates.
Serious staph infections may lead to:
Organ failure and death may result from untreated MRSA infections.
Call your health care provider if:
Careful attention to personal hygiene is key to avoiding MRSA infections.
Siegel JD, Rhinehart E, Jackson M, Chiarello L; Healthcare Infection Control Practices Advisory Committee.
Nicolle L. Community-acquired MRSA: a practitioner's guide. CMAJ. 2006;175:145.
Centers for Disease Control and Prevention.