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 infections, far more than previously thought, the study's data suggest.
The Chicago Tribune obtained the results during the weekend from the Association for Professionals in Infection Control and Epidemiology, which is releasing the report today. The author is Dr. William R. Jarvis, former acting director of the hospital infections program at the federal Centers for Disease Control and Prevention.
The findings come amid mounting public concern about 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 wake-up call to health care workers across America," said Kathy Warye, the association's executive officer.
It is the largest, most comprehensive survey of MRSA in health care facilities to date. 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.
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. 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 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 and even weeks.
The new survey 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 MRSA prevalence rate of 46 per 1,000 patients.
The most widely cited previous study, published by CDC researchers in June 2005, had estimated that the MRSA infection rate in in-patient hospitals was 3.9 per every 1,000 patients. Based on that rate, it estimated about 126,000 patients each year were infected with the superbug.
The new report didn't translate its findings into actual numbers, but its author outlined a means of doing so to the Tribune.
The calculation involves 35.2 million people hospitalized in the U.S. in 2005, the latest year for which information is available. Applying the prevalence rates in the new study, the data suggests that 1.2 million hospital patients are afflicted with MRSA each year and that 423,000 more patients are colonized with the superbug.
This is an estimate only, subject to the accuracy of the numbers reporting by infection control practitioners and the limitations of a "single point in time" snapshot of the data, said Jarvis, the study's author. Many hospitals don't routinely test patients to see if they're colonized with MRSA, he noted.
Previously, the CDC has said at least 5,000 patients die after being infected by MRSA. 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. Using the new estimates, that suggests as many as 119,000 hospital patients each year may be felled by the superbug.
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 elsewhere.
"This suggests that MRSA has become a problem throughout the institution, and that [hospital staff] may need to look for it beyond the ICU," Jarvis said.
Judith Graham writes for the Chicago Tribune.