Spreading bacteria surprise doctors

A once-rare drug-resistant staph bacterium now appears to cause more than half of all skin infections treated in U.S. emergency rooms, say researchers who documented the superbug's startling spread in the general population.

Many victims mistakenly thought they just had spider bites that wouldn't heal. Only a decade ago, these germs were hardly ever seen outside of hospitals and nursing homes.

Doctors also were caught off-guard — most of them unwittingly prescribed medicines that do not work against the bacterium.

"It is time for physicians to realize just how prevalent this is," said Dr. Gregory Moran of Olive View-UCLA Medical Center, who led the study.

Another author, Dr. Rachel Gorwitz of the Centers for Disease Control and Prevention, said: "I think no one was aware of the extent of the problem."

Skin infections can be life-threatening if bacteria get into the bloodstream. Drug-resistant strains can also cause a deadly lung disease known as necrotizing pneumonia.

The CDC paid for the study, published in today's New England Journal of Medicine. Several authors have consulted for companies that make antibiotics.

Researchers analyzed all skin infections among adults who went to hospital emergency rooms in 11 U.S. cities in August 2004. Of the 422 cases, 249, or 59 percent, were caused by methicillin-resistant Staphylococcus aureus, or MRSA. Such bacteria are impervious to the penicillin family of drugs long used for treatment.

The proportion of infections due to MRSA ranged from 15 percent to as high as 74 percent in some hospitals.

The germ typically thrives in health-care settings where people have open wounds and tubes. But in recent years, outbreaks have occurred among prisoners, children and athletes, as the germ spreads through skin contact or shared items such as towels. Dozens of people in Ohio, Kentucky and Vermont recently got MRSA skin infections from tattoos.

The staph was resistant to antibiotics routinely used to treat skin and soft-tissue infections, such as erythromycin; cephalexin, sold as Keflex; and dicloxacillin, sold as Diclocil, scientists said.

Most of the infections were more or less susceptible to other antibiotics, including clindamycin, tetracycline, rifampin and sulfa drugs. In addition, the study said, many drug-resistant infections can be cured by surgically lancing and draining them.

In an editorial accompanying the study, Dr. M. Lindsay Grayson, an infectious-disease expert at the University of Melbourne in Australia, said surgical drainage should become "the priority intervention" because the effectiveness of drug treatments varied.

The study was done in Albuquerque, N.M.; Atlanta; Charlotte, N.C.; Kansas City, Mo.; Los Angeles; Minneapolis; New Orleans; New York; Philadelphia; Phoenix; and Portland.