Bathers, beware. A trip to the beach could yield more than a damaging sunburn. According to a recent study, all nine sampled beaches in Washington State contained strains of the virulent methicillin-resistant Staphylococcus aureus (MRSA) bacteria—or related methicillin-resistant coagulase-negative Staphylococci—in the sand or water.

The so-called superbug can cause severe infection and is resistant to some antibiotic treatments. It is most closely associated with hospitals, where it was responsible for nearly 9,000 patient deaths in 2005, according to a study in The Journal of the American Medical Association. It has, however, been drawing increased attention in other settings.

"We were interested in answering where in the community, outside the health care system, could the average American pick this up," Marilyn Roberts, a professor of environmental and occupational health sciences at the University of Washington in Seattle and the study leader, told Bloomberg News.

Swimmers at subtropical beaches run about a 37 percent chance of being exposed to staph bacteria, according to research from the University of Miami, presented earlier this year at the American Association for the Advancement of Science (AAAS) annual conference in Chicago. That team found, however, that only 3 percent of the strains they collected were of the antibiotic-resistant variety.

The University of Washington study, presented at the Interscience Conference on Antimicrobial Agents and Chemotherapy in San Francisco on Saturday, was a cursory survey, which used small sample sizes and didn't investigate how the bug might be getting to the beaches. "The findings suggest that there's probably a lot more out there than what we were able to detect," Roberts told Bloomberg.

The MRSA strains that the researchers found appeared to be of the hospital-acquired variety, rather than the community-acquired one, raising questions about how they ended up at the beaches—none of which were close to a hospital. "Where all these organisms are coming from and how they are getting seeded, we don't know," Roberts told the Los Angeles Times.

Roberts and her colleagues don't recommend skipping the beach altogether (pools have also been found to be reservoirs of staph). But they do note that open wounds should be well covered, and sand should be washed off the body. Researchers from the University of Miami study note that those who have compromised immune systems are at a greater risk.

To avoid staph infections of any kind, bathers should shower before and after hitting the beach, recommends Paul Fey, an associate professor at the University of Nebraska Medical Center and associate director of the Clinical Microbiology Laboratory in Omaha, who wasn't involved with the research. People can spread staph to other swimmers but also to other parts of their own bodies. Staphylococcus epidemidis resides on the skin and rarely causes infection, but about 30 to 35 percent of people, he says, carry the aureus variety in mucus membranes and elsewhere on the body. "We're colonized," he says.

Image courtesy of mikebaird via Flickr