MRSA Strain on the Rise in Hospitals

Study Shows Community-Associated MRSA Is Spreading in Health Care Facilities

By Bill Hendrick
WebMD Health News

Reviewed By Louise Chang, MD

Nov. 24, 2009 -- A potentially dangerous and rapidly spreading strain of the "superbug" MRSA poses a much greater public health threat than previously thought, new research shows.

Community-associated MRSA (CA-MRSA) is spreading in hospitals and other health care facilities, according to a study in the December issue of Emerging Infectious Diseases.

The CA-MRSA strain of superbug can be picked up in fitness centers, schools, and other public places, and is increasing the already significant burden of MRSA (methicillin-resistant Staphylococcus aureus) in hospitals, the researchers report.

CA-MRSA and hospital-associated MRSA (HA-MRSA) are bacteria resistant to most common antibiotics.

HA-MRSA infections occur mostly in hospitals and other health care settings, including dialysis centers and nursing homes, and often strike mostly older adults, people having invasive medical procedures, and people with weakened immune systems.

CA-MRSA is a leading cause of serious skin and soft tissue infections, entering the body through scrapes and cuts, the researchers say.

The study, which analyzed data from more than 300 microbiology labs across the U.S., found a sevenfold increase in the proportion of CA-MRSA in outpatients between 1999 and 2006.

This community-associated strain is making its way into hospitals, the researchers say, increasing threats to patient safety because patients and their doctors move back and forth between inpatient and outpatient units of hospitals.

"This emerging epidemic of community-associated MRSA strains appears to add to the already high MRSA burden in hospitals," Ramanan Laxminarayan, PhD, MPH, a senior fellow at Extending the Cure, a project at the Resources for the Future think tank in Washington, D.C., says in a news release.

This major increase in CA-MRSA, the researchers say, has become a major concern.

Over the length of the study, the scientists report finding that the proportion of MRSA had increased more than 90% among outpatients with staph, and now accounts for more than 50% of all Staphyloccus aureus infections.

This was due, the findings suggest, almost entirely to an increase in CA-MRSA strains.

Similar increases in inpatients suggest these strains are spreading rapidly into hospitals.

"MRSA has generally been a significant problem only in hospitals," says Eili Klein, MA, the lead author of the report and also a researcher at Resources for the Future. "But the findings from this study suggest there is a significant reservoir in the community as well."

This suggests that the increased cases of CA-MRSA are causing that bug to spread from the community into hospitals, Klein says.

Hospitals need to take steps to stop this by stepping up infection control procedures, the researchers say, adding that the best way to contain MRSA and other superbugs is through surveillance and regular efforts aimed at infection control.

"Community-associated methicillin-resistant Staphylococcus aureus has become a major problem in U.S. hospitals already dealing with high levels of hospital-associated MRSA," the researchers write. They conclude that "more rapid diagnostic methods are urgently needed to better aid physicians" in fighting MRSA.

SOURCES: News release, Emerging Infectious Diseases, Burness Communications.

Klein, E. Emerging Infection Diseases, December 2009; vol 15.

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