This paper almost slipped by me. It was published quietly a few weeks ago, and it’s a little eyebrow-raising. From EuroSurveillance, the open-access peer-reviewed bulletin of the European Centre for Disease Prevention and Control (Europe’s CDC): The ST398 strain of MRSA, better know as “livestock-associated MRSA” or just “pig MRSA,” has been found for the first time in milk in England. (And therefore probably in cows, or at least on farms.)
Apparently there has been an ongoing study looking for any evidence of MRSA in UK cows, possibly because of this news from last year (of which more in a minute). Between last January and July, the program tested 1,500 samples of milk from farms’ bulk tanks — that’s the cooler in which milk from a number of cows is collected until it can be picked up by a truck for processing — and found seven of the samples were contaminated by MRSA.
All seven isolates were MRSA ST398, the livestock-associated strain. Three came from one farm, so five farms had MRSA in their tanks. According to the paper, this is the first discovery of ST398 in the UK other than one finding in horses in 2009.
Some background: ST398 represents what I think of as the “third epidemic” of MRSA, dating from 2004 and following on hospital-associated (dating from the 1960s) and community-acquired (dating from the 1990s). I told the long story of its emergence and international spread in the book Superbug, but briefly:
This strain was discovered in 2004 thanks to the care with which the Netherlands checks for MRSA in people about to be hospitalized; it was found in a toddler whose family were pig farmers, and subsequently in their friends, also farmers, and then in their pigs and their friends’ pigs also.
In the eight years since, it has spread into health care workers and hospitalized patients, into people with no connection to farming, and then into retail meat, in Europe, Canada and in the United States.