Study paints picture of rampant "superbug"

CHICAGO — As many as 1.2 million hospital patients are infected with dangerous, drug-resistant staph infections each year, almost 10 times more than previous estimates, based on findings from a major new study.

And 48,000 to 119,000 hospital patients a year may be dying from methicillin-resistant staphylococcus aureus, or MRSA, infections — far more than previously thought, the study's data suggest.

The Chicago Tribune obtained the results from the Association for Professionals in Infection Control & Epidemiology, which is releasing the report publicly today. The author is Dr. William Jarvis, former acting director of the hospital-infections program at the Centers for Disease Control and Prevention.

The findings come amid mounting public concern over the spread of antibiotic-resistant bacteria in health-care facilities and community settings. Medical experts consider the rise of so-called "superbugs" such as MRSA, a leading cause of deadly blood infections and pneumonias, one of the most alarming public-health threats in the nation.

"We're hoping this survey is a wakeup call to health-care workers across America," said Kathy Warye, the association's executive officer.

The new study is the largest, most comprehensive survey to date of MRSA in health-care facilities. It's based on surveys sent last year to 10,000 infection-control practitioners, including doctors and nurses, in hospitals, nursing homes and rehabilitation facilities. Because the resulting numbers are dependent on the accuracy of what those practitioners reported, they're only an estimate.

Health-care professionals were asked to select one day between Oct. 1 and Nov. 10, 2005, and report all known MRSA cases in their institutions on that date. More than 1,200 hospitals and 100 nursing homes and rehabilitation facilities responded, supplying data about patients with MRSA infections and patients colonized with the bacteria.

People colonized with MRSA typically carry it in their nose without being symptomatic. They're at risk of passing the superbug on to others unknowingly, by wiping their nose and then touching a table that a doctor or nurse later touches, for instance. MRSA can live on surfaces for days or even weeks.

The findings haven't been peer reviewed, as is standard in scientific publications.

But the new survey would seem to confirm what's been observed anecdotally for several years — that MRSA is rampant in health-care facilities.

It found that 34 of every 1,000 patients in the survey had active MRSA infections and that 12 were colonized with the superbug, for a total prevalence rate of 46 per 1,000 patients.

The calculation involves 35.2 million people hospitalized in the U.S. in 2005, the latest year for which data are available.

Applying the prevalence rates in the new study, the data suggest that 1.2 million hospital patients are afflicted with MRSA each year and that another 423,000 patients are colonized with the superbug.

The most widely cited previous study, published by CDC researchers in June 2005, had estimated that only 126,000 hospital patients have MRSA infections. That report suggested the MRSA infection rate in inpatient facilities was 3.9 per every 1,000 patients.

The new study was different in that it sampled a larger, more diverse set of health-care facilities.

"Most hospital leaders are paying very close attention to infections within their institutions. ... But I think this tells us is that MRSA is an even bigger problem than we thought it was," said Nancy Foster, vice president of quality and patient-safety policy at the American Hospital Association, after reviewing an advance copy of the APIC report.

Dr. John Jernigan, a medical epidemiologist at the CDC and the agency's lead expert on MRSA, said he "applauded the study" even though he hadn't yet examined its results or its methodology. Jernigan has co-authored several articles on MRSA with Jarvis in leading infection-control publications.

"Everything we're finding is telling us the same thing: MRSA is an enormous problem in health-care facilities, more needs to be done to prevent it, and hospitals need to make infection control more of a priority," Jernigan said.

The CDC has said previously that at least 5,000 patients die after being infected by MRSA at surgical sites, in their blood, or in their lungs, among other locations. That's a mortality rate of 4 percent, assuming a base of 126,000 patients. Using new prevalence estimates of 1.2 million MRSA patients a year, it suggests that 48,000 patients may die annually of MRSA.

There is considerable uncertainty about the true mortality rate associated with MRSA, however, and it may be as high as 10 percent, said Dr. Lance Peterson, director of infectious-disease research at Evanston Northwestern Healthcare in Evanston, Ill.

Using the new estimates, that suggests as many as 119,000 hospital patients each year may be felled by the superbug.

An important finding in the new study suggests hospitals may not be focusing infection-control strategies on the right locations. While earlier research has indicated intensive-care units are hot spots of infection, this report shows that 67 percent of patients with MRSA infections were on medical wards.

There is strong consensus about the steps hospitals need to take to control MRSA, said Dr. Don Goldmann, a senior vice president at the Institute for Healthcare Improvement in Boston.

All health-care workers should practice rigorous hand-washing, and all institutions should have robust programs for disinfecting medical equipment and patient rooms, he said. When patients are known to have MRSA, staff should wear gowns and gloves. And patients deemed at risk of carrying MRSA should be screened.

The Associated Press contributed to this report.