From 2005 to 2008, the number of new infections caused by MRSA — the deadly methicillin-resistant Staphylococcus aureus — fell by an average of 9.4% each year in hospitals and of 5.7% each year in other health-care facilities.
That good news is based on data collected over four years of active surveillance in nine U.S. metropolitan areas, and reported today by CDC researchers writing in the Journal of the American Medical Association. A total of 21,503 MRSA cases were reported in the catchment area from the beginning of 2005 to the end of 2008. The vast majority of those infections were in hospitals or other health-care settings, but, throughout, the rate of new infections per 10,000 people showed a steady downward trend.
The research team reports that, “the reasons for the observed decrease in incidence of invasive health care-associated MRSA infections [are] not known,” but that, probably, ”a number of factors” contributed. In 2006, the CDC published a 74-page manual on preventing the spread of drug-resistant organisms in health care, amid fear at that time over the growing number of these hard-to-treat infections — especially MRSA. The document reported early successes from around the world, especially from western Europe, in techniques to limit MRSA spread. It’s not unlikely, then, that similar precautions were adopted by U.S. health-care facilities soon after. The CDC has recommended not just treatment for MRSA with ever-more-potent antibiotics, but rather prevention by — for example — washing hands more frequently, isolating sick patients immediatley, and, when necessary, temporarily closing contaminated areas of a hospital. In addition, the authors of the new JAMA paper write, general improvements in central-venous-line infection control can contribute a great deal, since most MRSA infections in U.S. health-care facilities are blood-stream infections.
The 9.4% and 5.7% annual declines in MRSA incidence translate into a cumulative 28% drop in new infections in hospitals over the four years from 2005 to 2008, and a 17% drop in other health-care settings. All rates were adjusted to be net of changes in age and race composition of the surveillance population.