CHICAGO - Aggressive, drug-resistant staph infections caught in hospitals or from medical treatment are becoming scarcer, another sign of progress in a prevention effort that has become a national public health priority.
The decline was seen in a federal study of methicillin-resistant staph, or MRSA. The bug often causes only a boil or skin infection. But researchers in the study focused on invasive cases that can become deadly, invading the bloodstream, flesh, lungs, and bones.
Researchers found that in nine metro areas, cases of MRSA fell about 16 percent between 2005 and 2008. That translates to a drop to 26 cases per 100,000 people from about 32 cases per 100,000.
The results suggest aggressive efforts to stop the germ from spreading are working, researchers said. Such efforts include better hand-washing by doctors and nurses, and testing for MRSA when patients are admitted to the hospital.
"We're very encouraged by the results," said Dr. Alexander Kallen of the Centers for Disease Control and Prevention, the study's lead author. But he added, "It's still too early to celebrate. A lot of work needs to be done about better ways to eliminate MRSA."
The researchers focused on invasive MRSA in hospital patients or those who recently were treated in a hospital or other health-care setting, including kidney dialysis patients.
This decline in cases follows another CDC report last year that found invasive MRSA infections in intensive care units had fallen.
Although the overall rate declined, skin and soft-tissue infections remained mostly unchanged; these include flesh-eating infections that can be disfiguring and even deadly. Still, these cases were rare in the study.
Also, the report didn't address infections in schools, locker rooms, and other ordinary settings. Some reports have suggested those may be on the rise.
Cases in the community are "a tougher nut to crack" because there's more uncertainty about what makes people outside health-care settings vulnerable to MRSA, said Dr. Jaime Belmares, an infectious-disease specialist at Loyola University Medical Center in Maywood, Ill.
Loyola is among hospitals around the country that have begun testing all incoming patients for MRSA, and then isolating and treating these who have it.
Dr. Belmares said incidence of MRSA at his hospital has fallen since it launched universal testing in 2007.
Their report is in Wednesday's Journal of the American Medical Association.