Mark Holmes of the department of veterinary medicine at Cambridge University, who first identified MRSA in milk in 2011, said the latest finding of a different strain -- MRSA ST398 in seven samples of bulk milk from five British farms -- was a concern.
"This is definitely a worsening situation. In 2011 when we first found MRSA in farm animals, the Department of Environment, Food and Rural Affairs initially didn't believe it. They said we don't have MRSA in the dairy industry in this country," Holmes told The Independent.
"Now we definitely have MRSA in livestock. What is curious is that it has turned up in dairy cows when in other countries on the continent it is principally in pigs. Could it be in pigs or poultry in this country? We don't know."
Experts say there is no risk of MRSA infection to consumers of milk or dairy products so long as the milk is pasteurized, but there is a risk for farmhands, veterinarians and slaughterhouse workers, who may become infected via contact with the livestock and then transmit the bug to others.
The superbug can cause serious infections in humans, which are difficult to treat, require stronger antibiotics, and take longer to resolve.
Supermarkets exert pressure on farmers to use antibiotics to prevent cows from getting mastitis, an infection of the udder, that might interrupt the milk supply, Holmes said, common sense tells us that anything we can do to reduce use of antibiotics will reduce the growth of resistant bugs."