"This is a welcome piece of information that emphasizes that this is a huge problem in health care facilities, and more needs to done to prevent it," said Dr. John Jernigan, an epidemiologist with the US Centers for Disease Control and Prevention.
At issue is a strain of bacteria known as Methicillin-resistant Staphylococcus aureus, which cannot be tamed by certain common antibiotics. It is associated with sometimes-horrific skin infections, but it also causes blood infections, pneumonia, and other illnesses.
The potentially fatal germ, which is spread by touch, typically thrives in healthcare settings where people have open wounds. But in recent years, "community-associated" outbreaks have occurred among prisoners, children, and athletes, with the germ spreading through skin contact or shared items such as towels.
Past studies have looked at how common the germ is in specific patient groups, such as emergency room patients with skin infections in 11 US cities, dialysis patients, or those admitted to intensive care units in a sample of a few hundred teaching hospitals.
It's difficult to compare prevalence estimates from the different studies, analysts said, but the new study suggests the superbug is eight to 11 times more common than some other studies have concluded.
The new study was different in that it sampled a larger and more diverse set of healthcare facilities. And it counted cases in which the strain was present in a patient and not necessarily causing disease.
The infection control professionals' association sent surveys to its more than 11,000 members and asked them to pick one day from Oct. 1 to Nov. 10, 2006, to count cases of the infection. They were to turn in the number of all the patients in their health care facilities who were identified through test results as infected or colonized with the germ.
The final results represented 1,237 hospitals and nursing homes -- or roughly 21 percent of US inpatient health care facilities, association officials said. The researchers concluded at least 46 in every 1,000 patients had the germ.
About 34 per 1,000 were infected with the germ, meaning they had skin or blood infections or some other clinical symptom. And 12 per 1,000 were "colonized," meaning they had the infection but no illness.
