A nasty, drug-resistant bacterium has been creeping out of hospitals and into communities.
Methicillin-resistant Staphylococcus aureus (MRSA) can cause skin infections and a severe pneumonia.
The non-drug-resistant form of the bacterium commonly co-exists with humans quietly, living on the skin or in the nose of about 30 percent of the population. The drug-resistant form seems to live, also in a quiet, innocuous fashion, on about 1 percent of people.
When MRSA gets under the surface of the skin, it starts off like a spider bite, and can progress to boils or abscesses. Sometimes there are many sites of infection. Most skin infections seem to resolve on their own, as the body's immune system clears them up. However, sometimes MRSA can spread through the bloodstream, causing life-threatening complications like pneumonia.
MRSA is transmitted by direct contact with other people or through hands touching a surface or object that has become contaminated. Crowded living conditions, such as among military recruits and prisoners, and poor hygiene increase the risk of transmission. Athletes also seem to be at risk.
Having an impaired immune system is also a risk for getting MRSA infections. Common causes of poor immune function are diabetes, cancer and being on steroid medications. If you get a skin infection, you can't know if it's MRSA without having a health care provider do a culture of the wound. A lab can identify the bacteria and which antibiotics it is susceptible to.
The first treatment for a MRSA abscess is drainage of the pus. This usually means making an incision in the skin over the area and letting it drain. Many people will get better with this step alone. Incising an abscess also has the advantage of letting out the stuff you have to culture. MRSA is still resistant to many antibiotics, and is always resistant to an antibiotic health care providers frequently hold in reserve called vancomycin. Vancomycin must be administered intravenously.
And this is the essence of why this bacterium is dangerous, and a public health hazard. When treating infections, we now sometimes have to start with vancomycin, a very expensive drug that generally requires hospitalization. If we aren't paranoid enough about it, a case might slip through the cracks and cause devastation in some unlucky person.
And the cost will do bad things to the health care system. Physicians will start practicing defensively, not wanting to be sued for undertreating what later turns out to be MRSA. And excessive use of vancomycin means that Staph. aureus, and other bacteria, will probably develop resistance to that drug, too. A few cases of vancomycin resistant Staph. aureus have already appeared in the country. Don't worry, there are still antibiotics left, but it's an arms race.
Interestingly, research indicates that the current version of community-acquired MRSA is a descendant of a similar bacterium that caused widespread skin infections in the 1950s, and then somehow went underground. That infection, then called "phage type 8 0/8 1," was eliminated when synthetic penicillins arrived on the market in the 1960s.
The new community-acquired MRSA probably qualifies as an actual emerging epidemic. A research team in Denmark, for example, estimates that cases are doubling about every six months.
You can blame community MRSA on the overuse of antibiotics. Frequently patients who present to a primary care office with a respiratory infection expect antibiotics, and many physicians find it hard to say no. Constant exposure to antibiotics causes bacteria to become resistant to them through natural selection -- the bacteria that aren't killed by the chemical live on to make more bacteria like themselves.
Antibiotics are available in some countries without a prescription. Also, they are commonly added to animal feeds to stimulate growth, and bacteria in those settings become resistant, too.
You can reduce your chances of getting MRSA by some common-sense hygiene. Wash your hands frequently. Avoid contact with other people's wounds or anything that the wound has touched. Avoid sharing personal items that touch the body like razors and sports equipment. Clean sports equipment regularly.
Dr. Mike Merrill is an internist practicing in Buffalo. His column appears once a month on this page. E-mail your comments to him at email@example.com.