Scientist Say: Infectious Bacteria Found on Northwest Beaches

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By David Olmos

Sept. 12 (Bloomberg) — Drug-resistant bacteria that causes serious infections and is most commonly spread in hospitals was found on nine beaches in Washington state, scientists said.

Samples from water and sand collected from 11 public beaches near Puget Sound near Seattle and in California were tested for a germ known as methicillin-resistant Staphylococcus aureus, or MRSA, and a closely related drug-resistant organism, according to a study reported today at a meeting of infectious disease doctors in San Francisco.

MRSA is found in about 5 percent of hospital patients, and accounts for almost two-thirds of skin infections in emergency rooms, up from just 2 percent 35 years ago, according to the Rockville, Maryland-based U.S. Agency for Healthcare Research and Quality. Scientists are studying how the bacteria spread away from hospitals, nursing homes and kidney dialysis centers.

“We were interested in answering where in the community, outside the health care system, could the average American pick this up,” said Marilyn Roberts, the study’s lead author, in a telephone interview. “We found MRSA in a lot more places than we thought we would.”

Roberts, a researcher at the University of Washington’s School of Public Health in Seattle, presented the findings today at the Interscience Conference on Antimicrobial Agents and Chemotherapy in San Francisco.

Strain of Staph Infections

Staphyloccus aureous is a strain of so-called staph infections that are typically carried on the skin or in the nose of healthy people. The first U.S. MRSA infection was reported in 1968, according to the National Institutes of Health. The bacteria are resistant to common first-line antibiotics, such as penicillin and amoxicillin, and can lead to a serious form of pneumonia and death. The most vulnerable patients are those with weakened immune systems and those undergoing surgery, Roberts said.

Scientists have known that staph can spread in water, such as in swimming pools, Roberts said. And previous studies have found MRSA present in warmer waters, such as South Florida.

The study by University of Washington researchers was the first to look at the presence of MRSA in the water and the sand at beaches, Roberts said. MRSA or the closely related germ, called Methicillin-resistant coagulase-negative Staphylococci, were found at all nine of the Washington sites. The bacteria weren’t discovered at the two California beaches. The germs may not have been found at the California sites because the samples were collected on a single day and the sample size was “skimpy,” Roberts said.

Question of Transmission

The study didn’t attempt to determine how MRSA was getting into the water or sand, Roberts said. Possible explanations include beachgoers shedding the bacteria from their bodies, transmission from birds and animals and run-off from hospital locations, although none of the sampling sites was near a hospital, she said.

“When we started the study, we didn’t necessarily think we’d find MRSA at all,” Roberts said. “The findings suggest that there’s probably a lot more out there than what we were able to detect” considering the relatively small samples taken, she said.

Further studies may analyze where people with MRSA infections were exposed to the bacteria, she said.

To contact the reporter on this story: David Olmos in San Francisco at

Last Updated: September 12, 2009 12:45 EDT

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