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David Baxter PhD

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MRSA: Understand your risk and how to prevent infection
By James Steckelberg, M.D.,Mayo Clinic
Oct 30, 2007

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 recently gained increased media attention. The attention is in part because of an October 2007 Centers for Disease Control and Prevention (CDC) report on MRSA. MRSA has also played a role in several deaths among otherwise healthy school-age athletes. Are such 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.
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 suddenly 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, including the death of a previously healthy 17-year-old football player in Moneta, Va. The combination of those school 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)
Is MRSA spreading rampantly, or is it just being monitored more closely?
Staph infections have always been among the most common, and potentially the most serious, infections. The proportion of those infections now resistant to antibiotics (MRSA) has risen in comparison with those without such antibiotic resistance. This may be because of overuse and misuse of antibiotics and transmission of the virus between hospital patients. Also, the number of people at risk of such infections ? such as those with a chronic illness, on kidney dialysis, exposed in a health care setting, or who use intravenous catheters or other implanted medical devices ? has steadily risen with changes in health care and an aging population.

What's the best defense against MRSA in the community?
Protecting yourself from MRSA in the community ? which might be just about anywhere ? may seem daunting, but these common-sense precautions can help reduce your risk:

  • Wash your hands. Careful hand washing remains your best defense against germs. Scrub hands briskly for at least 15 seconds, then dry them with a disposable towel and use another towel to turn off the faucet. Carry a small bottle of hand sanitizer containing at least 62 percent alcohol for times when you don't have access to soap and water.
  • Keep personal items personal. Avoid sharing personal items such as towels, sheets, razors, clothing and athletic equipment. MRSA spreads on contaminated objects as well as through direct contact.
  • Keep wounds covered. Keep cuts and abrasions clean and covered with sterile, dry bandages until they heal. The pus from infected sores may contain MRSA, and keeping wounds covered will help keep the bacteria from spreading.
  • Shower after athletic games or practices. Shower immediately after each game or practice. Use soap and water. Don't share towels.
  • Sit out athletic games or practices if you have a concerning infection. If you have a wound that's draining or appears infected ? for example is red, swollen, warm to the touch or tender ? consider sitting out athletic games or practices until the wound has healed.
  • Sanitize linens. If you have a cut or sore, wash towels and bed linens in a washing machine set to the "hot" water setting (with added bleach, if possible) and dry them in a hot dryer. Wash gym and athletic clothes after each wearing.
  • Get tested. If you have a skin infection that requires treatment, ask your doctor if you should be tested for MRSA. Doctors may prescribe drugs that aren't effective against antibiotic-resistant staph, which delays treatment and creates more resistant germs. Testing specifically for MRSA may get you the specific antibiotic you need to effectively treat your infection.
  • Use antibiotics appropriately. When you're prescribed an antibiotic, take all of the doses, even if the infection is getting better. Don't stop until your doctor tells you to stop. Don't share antibiotics with others or save unfinished antibiotics for another time. Inappropriate use of antibiotics, including not taking all of your prescription and overuse, contributes to resistance. If your infection isn't improving after a few days of taking an antibiotic, contact your doctor.
Is it necessary to sanitize buses and close schools for cleaning?
Most MRSA is spread through skin-to-skin contact or through shared items such as towels, razors and bandages. In most cases, it's not necessary to close schools unless an outbreak of MRSA cannot be controlled otherwise. It's possible that surfaces ? such as a bus seat ? may be contaminated for hours to days, but infection is not a likely result. Following the tips above is the most effective means of preventing MRSA infection.

If you suspect an MRSA infection, what should you do?
Closely watch minor skin problems ? pimples, insect bites, cuts and scrapes ? especially in children and older adults. If wounds become infected, see your doctor. Indications of an infected wound include increasing skin redness, swelling, warmth, tenderness, pus drainage and sometimes fever. If you test positive for staph infection, ask that the skin culture growing staph be tested for MRSA. Drugs that treat ordinary staph aren't effective against MRSA. Using these ineffective drugs could lead to serious illness and more resistant bacteria.
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