Tuesday, January 24, 2006
2 million in U.S. may carry staph; infections on the rise
The Dallas Morning NewsPublished on: 01/23/06
DALLAS — The first nationwide statistical snapshot of a worrisome infection estimates at least 2 million people in the country may be silently carrying a potentially dangerous bacterium. And a second study reports that the germ appears to be creeping into hospital patients at a steady pace.
The studies are the latest clues to the behavior of methicillin-resistant Staphylococcus aureus, or MRSA. Since its appearance in the general population in 1999, the infection has already become notorious for illness among inmates, children and professional athletes. Last September, MRSA spread among Katrina evacuees at a shelter in Dallas. The St. Louis Rams battled an outbreak that affected five players, who apparently passed the infection to members of the San Francisco 49ers.
On Friday, the Dallas County Department of Health and Human Services issued a warning about MRSA infections picked up in contaminated whirlpool footbaths at some area nail salons.
Despite high-profile attacks of MRSA, scientists had not been able to say exactly how widespread the bug might be. Most of the time, people carry staph bacteria in their noses without knowing it. Only when it slips through breaks in the skin does MRSA announce itself. It concerns doctors not only because of its potential to cause disease, but also because it resists many traditional treatments.
This month, in the Journal of Infectious Diseases, researchers from the U.S. Centers for Disease Control and Prevention report that about 32 percent of the American population harbors S. aureus. About 1 percent of that staph appears to be MRSA. That would mean between 1.2 million and 3.8 million people carry the more dangerous form.
The most likely staph carriers were children, though the MRSA form was most common among older people, especially women.
"It's become one of the dominant infections of childhood," said Dr. William Schaffner of Vanderbilt University School of Medicine, who wrote a commentary that appears with the study.
Dr. Schaffner also noted that the study was conducted in 2001, just as the organism was getting a foothold in the U.S. population, and later data point to an epidemic that has only grown. For example, about 10 percent of children who come to Vanderbilt are colonized with MRSA.
MRSA has been long known as a hospital menace. In 1999, however, MRSA infections began showing up in otherwise healthy people who had never been near a hospital. The bacterium even got its own acronym: CA-MRSA, for "community acquired" MRSA.
CA-MRSA bears some differences from its hospital-bound cousin. While it appears to be more susceptible to antibiotics, it has at times shown a greater knack for causing some of staph's more terrible consequences, such as a particularly deadly form of pneumonia. Most often, though, CA-MRSA causes skin infections.
The infection is making a renewed name for itself in hospitals. A second study of more than 1,200 intensive care units, to be published in the Feb. 1 issue of Clinical Infectious Diseases, notes that 64 percent of staph infections now appear to be caused by MRSA. In 1992 the number was 36 percent.
Doctors are intensifying efforts to control the spread of MRSA, which thrives in places where people crowd together and which takes advantage of lapses in hygiene.
"It's not fancy drugs that we need in terms of prevention," said Dr. Jane Siegel of Children's Medical Center.