Causes

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.

• 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.

Symptoms

Staph skin infections cause a red, swollen, and painful area on the skin. There may be drainage of pus or other fluids from the site. Symptoms are more likely to occur where the skin has been cut or rubbed, or in areas where there is more body hair.

When patients get MRSA in health care facilities, the infections tend to be severe. These staph infections may be in the bloodstream, heart or lungs, urine, or at the site of a recent surgery. Symptoms of these severe infections include:

• Chest pain
• Chills
• Cough
• Fatigue
• Fever
• General ill feeling (malaise)
• Headache
• Muscle aches
• Rash
• Shortness of breath

Exams and Tests

Depending on your symptoms, your doctor may recommend the following tests to detect and confirm the bacteria causing the infection:

• Blood culture
• Culture from the infected site
• Gram stain and culture of the drainage (fluid) from the infection
• Sputum culture
• Urine culture

Treatment

Draining the skin infection may be the only treatment needed for a local skin MRSA infection. This procedure should be done at the doctor's office. Do not try to pop open or drain the infection yourself. Keep any sore or wound covered.

If you are given antibiotics, be sure to take all the doses, even if you feel better. Not finishing the full course of antibiotics can allow an infection that seemed to be gone to come back (relapse).

More serious MRSA infections are becoming harder to treat. Your doctor will follow guidelines about which antibiotics should be used.

Other treatments may be needed for more serious infections. If you are not already in the hospital, you may be admitted. Treatment may involve:

• Fluids and medications given through a vein
• Kidney dialysis (if kidney failure occurs)
• Oxygen

Support Groups

For more information about MRSA, see the Centers for Disease Control web site: www.cdc.gov/mrsa/.

Outlook (Prognosis)

How well a person does depends on the severity of the infection and their overall health. MRSA-related pneumonia and blood infections are associated with high death rates.

When to Contact a Medical Professional

Call your health care provider if you have any wound that seems to get worse instead of healing.

Prevention

Follow these steps to avoid MRS infections and prevent it from spreading:

• Keep your hands clean by washing them thoroughly with soap and water or using an alcohol-based hand sanitizer.
• Keep cuts and scrapes clean and covered with a bandage until they heal.
• Avoid contact with other people's wounds or bandages.
• Avoid sharing personal items such as towels or razors.

Some simple steps for athletes include:

• Cover all wounds with a clean bandage, and avoid contact with soiled bandages from other people.
• Clean your hands before and after playing sports. Shower right after exercising and do not share soap or towels with other people.
• If you share sporting equipment, clean it first with antiseptic solution and then use clothing or a towel between your skin and the equipment.
• Avoid common whirlpools or saunas if another participant has an open sore. Always use clothing or a towel as a barrier.
• Avoid sharing splints, bandages, or braces.
• Make sure that shared bathing facilities are clean.

Wash your hands often, especially if you are visiting someone in a hospital or long-term care facility.

When visiting MRSA patients, follow the facility's visitor policies. Casual contact -- such as kissing, hugging, and touching--is usually okay. Avoid touching catheters or wound sites. Wash your hands before leaving an infected person's room.

Make sure all doctors, nurses, and other health care providers wash their hands before examining you.

Alternative Names

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

References

Centers for Disease Control and Prevention. Methicillin-resistant Staphylococcus aureus (MRSA) infections. Accessed April 17, 2011.

Que YA, Moreillon P. Staphylococcus aureus (including staphylococcal toxic shock). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 195.

Update Date: 4/9/2012

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.