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Scientists announce discovery of new strain of MRSA

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June 3, 2011 at 2:47 a.m. EDT

As if the E. coli outbreak in Europe wasn't frightening enough, British scientists have announced the discovery of a new strain of a dangerous antibiotic-resistant bacteria that infects both humans and cows.

In a report being published online Friday in the journal The Lancet Infectious Diseases, researchers said they stumbled across the new strain of methicillin-resistant Staphylococcus aureus (MRSA) while studying udder infections in cows on British farms.

MRSA is a strain of the ubiquitous bacterium that usually causes staph infections that are easily treated with common antibiotics in the penicillin family, such as methicillin. Strains of the organism, however, that are impervious to such first-line antibiotics have been increasingly turning up in hospitals and in small outbreaks outside heath-care settings, such as among athletes, prison inmates and children.

In the new research, Mark Holmes of the University of Cambridge and colleagues came across a resistant strain of MRSA that did not have a gene known as mecA, which is what typically makes the organism resistant. An analysis of the specimens revealed that they had a different, previously unknown version of the gene.

The researchers then discovered the new strain in humans in Scotland, England and Denmark. It has subsequently been found in Ireland and Germany. And additional studies indicate it’s becoming more common, the researchers reported.

They stressed that the discovery does not mean that people can get infected by drinking pasteurized milk or consuming dairy products. But the resistant organism possibly could be spread through unpasteurized milk, Holmes told reporters during a briefing Thursday.

Moreover, the discovery means that tests currently used to diagnose the infection could miss cases of this strain, possibly delaying life-saving treatment. In addition, it's possible that cows may be a previously unrecognized source of infection, and that people who live and work on farms could pick it up there and spread it to others, the researchers said.