MRSA

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Methicillin-resistant Staphylococcus aureus (MRSA) is a type (strain) of staph bacteria that does not respond to some antibiotics that are commonly used to treat staph infections.

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

Staph. aureus is a common type of bacteria. In about 1 out of every 4 healthy people, the staph germ lives on the skin or in the nasal passages, but it does not cause any problems or infections. These people are said to be colonized with staph.

If the staph bacteria enter a person's body through a cut, sore, catheter, or breathing tube, it may cause an infection.

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• The infection can be minor and local (for example, a pimple), or more serious (involving the heart, lungs, blood, or bone).
• Serious staph infections are more common in people with a weak immune system. This includes patients in hospitals and long-term care facilities and people who are receiving kidney dialysis or cancer treatment.

In the past, most staph infections responded to a gorup of antibiotics called beta-lactams. These antibiotics include methicillin and other, more common antibiotics such as oxacillin, penicillin, and amoxicillin.

About 2 out of every 100 people carry a strain of staph that is resistant to these antibiotics. Being resistant means an antibiotic is unable to treat and cure an infection with this type of bacteria.

This strain of staph is called MRSA, or methicillin-resistant Staphylococcus aureus. MRSA infections often occur in people who are in the hospital or other health care setting. Those who have been hospitalized or had surgery within the past year are also at increased risk. MRSA bacteria are causing a higher number of the staph infections that begin in the hospital.

MRSA infections that occur in the community are seen in otherwise healthy people who have not recently been in the hospital. Most of these infections involve the skin.

• The infections have occurred among athletes who share equipment or personal items (such as towels or razors) and children in day care facilities.
• Members of the military and those who get tattoos are also at risk. The number of community-acquired MRSA cases is increasing.

Review Date: 06/09/2011
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Jatin M. Vyas, PhD, MD, Instructor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).