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- MRSA: Understand your risk and how to prevent infection
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MRSA: Understand your risk and how to prevent infection
By Mayo Clinic staff
MRSA — or methicillin-resistant Staphylococcus aureus — has been a problem in hospital and health care settings for years. But this highly drug-resistant bacterium has gained attention in recent years for its role in several deaths among otherwise healthy school-age athletes. Are MRSA infections on the rise? What are the real risks of MRSA infection for you or your child? And what can you do to protect against MRSA infection? James Steckelberg, M.D., an infectious disease specialist at Mayo Clinic, Rochester, Minn., answers these and other common questions about MRSA.
What is MRSA, and why is it sometimes referred to as a "superbug"?
- MRSA in hospitals. MRSA infection is caused by Staphylococcus aureus bacteria — often called "staph." Many years ago, a strain of staph emerged in hospitals that was resistant to the broad-spectrum antibiotics commonly used to treat it. Dubbed methicillin-resistant Staphylococcus aureus (MRSA), it has been called a "superbug" by the media because of its multiple drug resistance. MRSA can cause serious, sometimes fatal, infections that resist treatment with all but a few drugs — for example, vancomycin, linezolid or daptomycin. Some extremely rare strains of MRSA that are resistant even to vancomycin are starting to turn up in some hospitals.
- MRSA in the community. In the 1990s, a type of MRSA began showing up outside hospital settings — in the wider community. These strains aren't the same as those associated with health care settings and hospitals. Today, these forms of staph, known as community-associated MRSA, or CA-MRSA, are responsible for many serious skin and soft tissue infections and for a serious form of pneumonia. And while CA-MRSA initially was found more outside the hospital setting, that is changing. Strains of CA-MRSA are now found with increasing frequency in hospitals and other health-care settings.
A variety of staph bacteria are normally found on the skin or in the nose of about three in every 10 people at any given time. If you have staph on your skin or in your nose but aren't sick, you are considered to be "colonized" but not infected. Staph bacteria are generally harmless unless they enter the body through a cut or other wound, and even then they often cause only minor skin infections in healthy people. But sometimes, usually in older adults and people who are ill or have weakened immune systems, ordinary staph infections can cause serious illness.
Although 30 percent of the population may be colonized with ordinary staph at any given time, just a small percentage of those people are colonized with MRSA. Healthy people can be colonized with MRSA and have no ill effects. However, they can pass the germ to others by sharing items such as towels, clothing and athletic equipment.
Several antibiotics continue to be effective against MRSA in the community, but this type of MRSA is a newly evolved bacterium, and it may be a matter of time before some community associated strains become resistant to most antibiotics.
Why is MRSA in the news?
A CDC report published in an October 2007 issue of the Journal of the American Medical Association suggested that MRSA infections are more prevalent than previously thought. This doesn't necessarily represent an increase in MRSA, however, because MRSA has simply not been measured in this way before. At about the same time, news reports emerged of student staph infections and deaths in several states. The combination of those events and the new data is doubly distressing, especially for parents.
How did MRSA evolve from a mainly hospital problem to a community problem?
It isn't known how MRSA in the community has evolved. It didn't originate from the hospital variety. One explanation is that drug-resistant bacteria may have developed from the overuse and misuse of antibiotics.
The vast majority of MRSA infections — 85 percent — are still found in hospitals and other health care settings rather than in the community. However, clusters of community-associated MRSA skin infections have been found in athletes, military members, children, Pacific Islanders, Alaskan Natives, American Indians, men who have sex with men, and prisoners. Risk factors in these groups may include:
- Close skin-to-skin contact
- Openings in the skin such as cuts or abrasions
- Contaminated items and surfaces such as clothes and athletic equipment
- Crowded living conditions
- Poor hygiene (although even very clean people can get staph infections)
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