Deadly Superbug Evades Hospital Screening

March 11, 2008— -- Efforts to screen patients for drug-resistant staph infections at the time of their hospital admissions appear to be ineffective in stemming the spread of the potentially deadly "superbug" known as MRSA, new research suggests.

The finding is the latest bad news for the control of the bacteria MRSA — short for methicillin-resistant staphylococcus aureus. The germ, which doctors believe gained its drug-resistant properties from years of inappropriate antibiotic use, garnered headlines in October when researchers from the U.S. Centers for Disease Control and Prevention identified it as the culprit in an estimated 94,000 life-threatening infections and 18,650 deaths in 2005.

The latest research, published Tuesday in the Journal of the American Medical Association, shows that the stubborn bug appears to evade hospital screening efforts intended to keep it in check.

Between July 2004 and May 2006, researchers looked at more than 20,000 surgical patients at a Swiss teaching hospital. Roughly half were part of hospitalized groups in which all patients were screened for the disease upon admission. The other half were not subject to such screening measures.

What they found was that, screening or not, the levels of MRSA that spread were about the same for all patients — a finding that flies in the face of recommendations by top health policy makers and experts aimed at catching the disease early, before it can spread unchecked through hospitals.

Lead study author Dr. Stephan Harbarth of the University Hospital of Geneva in Switzerland said the new research reinforces the idea that antibiotics must be used more judiciously, particularly in the United States, in order to avoid the emergence of such drug-resistant infections.

"There's incredible antibiotic pressure in U.S. hospitals," Harbarth said. "Length of stay for patients is extremely short, and they get bombarded with antibiotics, so it helps to create favorable environment to select these resistant organisms."

Infectious disease experts, however, remained split on whether the results represent a blow to hospitals that have implemented such measures to limit MRSA's spread.

"I would not see this as a blow at all, rather a reinforcement that stringent, well-practiced infection control is the best way to defend against MRSA and other similar infections," said Dr. Ann Marie Kimball, director of the Asia Pacific Economic Cooperation Emerging Infections Network and professor of epidemiology at the University of Washington.

"Recall that MRSA actually migrated historically from the hospitals to the communities, so screening community admissions would not make sense," she noted, adding on the other hand that sharing information on the MRSA status of patients when transferring them from hospital to hospital could indeed have a positive impact on the spread of the disease.

Others said that screening was just one part of the equation — and it must be combined with other preventive measures, such as strictly enforced hand washing by medical personnel to see the most effect.

"Screening for MRSA, used selectively, has been successful in reducing spread in our institution, but needs to be done in conjunction with other measures," said Dr. Marcus Zervos, medical director of infection control for the Henry Ford Health System in Detroit.

And in this respect, said Dr. Barry Farr, professor emeritus of medicine at the University of Virginia, screening measures to detect the bug play an integral role.

"Based upon available scientific data, isolation of all colonized and infected patients was the highest rated control measure recommended by the CDC's 2006 guideline, and no other control measure comes close to having so much data documenting success," Farr said, adding that such isolation can only take place if patients who are infected with MRSA are identified early.

Putting Recommendations Before Results?

But other doctors said the new finding suggests that many hospitals may have been too quick to implement an additional, largely unproven admissions procedure that turned out to have a minimal role in controlling the spread of MRSA.

"Some people advocated 'catching the bug early … to reduce its spread,'" said Dr. Marvin Bittner, associate professor at the Creighton University School of Medicine in Omaha, referring to the new study. But he added that this was a controversial measure at best, and one that was not generally supported by the CDC.

"In my opinion, the decisions to screen patients for MRSA were political decisions and not medical decisions," agreed Clyde Thornsberry, chief scientific advisor for anti-infective services for Eurofins Medinet Inc. of Herndon, Va.

"My guess is that most infectious disease physicians and microbiologists would have predicted that the return would have been minimal."

Still, even lead author Harbarth said MRSA screening may have its place in hospitals — particularly when it comes to certain patients or populations that may be particularly vulnerable to the bacteria.

The study, Harbarth said, focused on "MRSA rates only in surgery, only in one hospital in Switzerland.

"Screening may still be useful in intensive care units or in hospitals with high infection rates, so there's a little word of caution."