Surviving the New Killer Bug

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The ubiquity of staph bacteria adds to the problem. The germs are part of the usual microscopic landscape of your outer and inner skin, including the mucus linings of the nose. Most of those bacteria don't cause illness, and in fact their presence is a good thing, since they can crowd out more dangerous pathogens. But every once in a while, the good guys take a beating, and one of the bad guys, like MRSA, takes hold, colonizing the skin.

Even when that happens, it doesn't necessarily signal an emergency. The skin, after all, is an effective barrier against many kinds of threats. But anytime you get a break in that barrier--even a tiny cut--there's a chance some bacteria will get inside and infect the wound. What makes MRSA germs particularly dangerous is that they excrete a potent toxin that attacks the skin, causing an abscess that's often mistaken for a spider bite. Normally, the body can wall that area off. But if the infection spreads, treatment with antibiotics may be called for.

And that's the problem. Doctors have grown used to prescribing antibiotics like oxacillin or cephalexin in that situation. It's not clear if that long-standing habit helped the bugs grow resistant in the first place. But what is abundantly clear is that those standard treatments are no longer effective.

There's another factor that makes the community-based MRSA so dangerous, one that has been revealed only recently by genetic analysis. In addition to their normal chromosomal DNA, staph and other bacteria like to mix and match genetic information by exchanging short strips of DNA called cassettes. Some of those cassettes carry genetic instructions to do two things at once: confer antibiotic resistance and make the host even more susceptible to infection. "MRSA is where resistance and virulence converge," says Daum.

What epidemiologists still can't explain, however, is how that particular bug manages to get around to so many cities and towns yet has left others relatively unscathed--at least so far. Cases of the new MRSA strain have only just started cropping up in New York City, for example. "We've been waiting for this to happen," says Dr. Betsy Herold of Mt. Sinai. "Now, we're in a unique position to watch it unfold and to find out why it's happening."

Meanwhile, there are things you can do to protect yourself (see box). To prevent more bugs from developing resistance, it's important to remember that not all skin infections need antibiotic treatment, even MRSA. "A garden-variety infection is still a garden-variety infection," says Dr. Philip Graham at New York-Presbyterian's Children's Hospital in New York City. "If your cuts and scrapes are acting like they always do, don't worry."

If, however, you or a loved one is running a high fever, has a lot of redness or shows signs that an abscess is forming, you need to get to a doctor right away. "It never hurts for a patient to say something like, Could this be an MRSA infection?" says Dr. Jack Edwards, chief of infectious disease at Harbor-UCLA Medical Center in Los Angeles. It could make all the difference in the world.