( mmunity. The other infections were form...)Resistant bacteria increasing source of muscle infection

It is important the doctors treating patients for skin infections such as cellulitis to use antibiotics that will cure the resistant forms of the bacteria, said Pannaraj.

"Be aware that this is out there," she said. "When someone comes in, doctors should be aware that this could be a muscle abscess."

Antibiotics that successfully treat MRSA include oral clindamycin and trimethoprim-sulfamethoxazole, which are usually used out of the hospital, and vancomycin or clindamycin, which is given intravenously, usually to hospitalized patients.

The form of MRSA that is acquired in the community spreads more easily than that usually caught in the hospital, said Pannaraj.

"That's why I am seeing it in otherwise healthy children," she said.

She and her colleagues are trying to find out why this particular form of the bacteria spreads so easily. Her studies are focusing on specific genes. One, pvl, permits holes to be poked into the cells, damaging them irreparably.

"There seems to be an association between bacteria carrying the pvl gene and the severity of disease," she said. However, she said, they have not yet determined whether the problem is this specific gene or another that is close to it.

Others who participated in this research include: Drs. Kristina G. Hulten, Blanca E. Gonzalez, Edward O. Mason, Jr., and Sheldon L. Kaplan, all of the section of infectious diseases in the department of pediatrics at Baylor College of Medicine and Texas Children's Hospital.