MRSA

Answer 1

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. aureusstrains 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.

Symptoms

Staph skin infections cause a red, swollen, and painful area on the skin. Other symptoms may include:

• Drainage of pus or other fluids from the site
• Fever
• Skin abscess
• Warmth around the infected area

Symptoms of a more serious staph infection may include:

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

Signs 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 of the drainage (fluid) from the infection
• Skin culturefrom the infected site
• Sputum culture
• Urine culture

Treatment

Draining the skin sore may be 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:

• Clindamycin
• Daptomycin
• Doxycycline
• Linezolid (Zyvox)
• Minocycline
• Tetracycline
• Trimethoprim-sulfamethoxazole (Bactrim, Bactrim DS, Septra, Septra DS)
• Vancomycin (Vancocin, Vancoled)

It is important to finish all doses of antibiotics you have been given, even if you feel better before the final dose. Stopping treatment early by not finishing the full course of antibiotics can lead to further drug resistance in the bacteria, or can cause an infection that seemed to be gone to come back (relapse).

Other treatments may be needed for more serious infections. The person may be admitted to a hospital. 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/.

Expectations (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.

Complications

Serious staph infections may lead to:

• Blood infection (also called blood poisoning or sepsis)
• Cellulitis
• Infection of the heart valves (endocarditis)
• Pneumonia
• Toxic shock syndrome

Organ failure and death may result from untreated MRSA infections.

Calling your health care provider

Call your health care provider if:

• A wound seems to get worse rather than heal
• You have any other symptoms of staph infection

Prevention

Careful attention to personal hygiene is key to avoiding MRSA infections.

• Wash your hands frequently, especially if visiting someone in a hospital or long-term care facility.
• Make sure all doctors, nurses, and other health care providers wash their hands before examining you.
• Do not share personal items such as towels or razors with another person -- MRSA can be transmitted through contaminated items.
• Cover all wounds with a clean bandage, and avoid contact with other people's soiled bandages.
• If you share sporting equipment, clean it first with antiseptic solution.
• Avoid common whirlpools or saunas if another participant has an open sore.
• Make sure that shared bathing facilities are clean.

References

Archer GL. Staphylococcal infections. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier. 2007: chap 310.

Centers for Disease Control and Prevention. Overview of community-associated MRSA. October 26, 2007. Accessed January 25, 2008

Nicolle L. Community-acquired MRSA: a practitioner's guide. CMAJ. 2006;175:145.

Siegel JD, Rhinehart E, Jackson M, Chiarello L; Healthcare Infection Control Practices Advisory Committee. Management of multi-drug resistant organisms in healthcare settings, 2006. US Centers for Disease Control and Prevention. Accessed January 25, 2008.

Answer 2

Definition

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.

Alternative Names

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

Causes, incidence, and risk factors

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

Signs 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/.

Expectations (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.

Calling your health care provider

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.

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.

Reviewed By

Review Date: 06/09/2011

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.