Organic farming champions the Soil Association this week issued a "wake up call" to the government over the issue, and called for a full scale investigation leading to major husbandry changes.
The SA alert was prompted by new research from the University of Cambridge revealing that the first cases of a 'superbug' variety of MRSA – classified as ST398 – had been found in UK livestock.
First identified in pigs in the Netherlands in 2003, MRSA ST398 has since become epidemic in European and North American pig populations and spread to poultry and cattle – but until now it had not been found in British livestock.
This superbug can cause serious and occasionally deadly infections in humans and is becoming a cause of mastitis in cows. Its high level of antibiotic resistance makes it difficult to treat, and the Cambridge scientists maintained that their finding was therefore 'of significance to both veterinary and human health'.
Testing 1500 samples of bulk milk, the Cambridge team found seven cases of MRSA ST398 in milk from five different farms in England, Scotland and Wales. Although there is no direct threat to human health from consuming milk, because pasteurisation will kill the bacteria, research from other countries has shown farmers, vets and abattoir workers are at increased risk.
The Soil Association pointed out recently published Defra research, which found that more than three-quarters of British dairy farms feed waste milk containing antibiotic residues to their calves.
This can include milk produced during the withdrawal period, after a cow has been treated with antibiotics, and is legally unfit for human consumption – and it is that antibiotic-loaded milk that the SA believes is encouraging the proliferation of resistant bugs in cattle.
SA policy adviser Richard Young said: "This should be a wake-up call for Defra. The European Food Safety Authority recently called on all Member States to carry out regular monitoring of poultry, pigs and dairy cattle for MRSA, but unlike other countries, the UK continues to ignore this request. We are lucky independent researchers identified this problem at an early stage. We are calling for comprehensive surveillance to be established before it gets out of hand.
"Defra must also urgently deal with the problem of waste milk containing high levels of antibiotic residues being fed to calves. There is strong evidence this has contributed to the spread of other superbugs, like ESBL E. coli, and it is also likely to make the MRSA problem on dairy farms much worse," said Mr Young.
"We are keen to work with the industry to address this challenge and call for a ban on feeding calves waste milk from cows that have recently received antibiotics, unless the milk can be treated to destroy antibiotic residues and kill resistant bacteria while ensuring the resulting milk is still sufficiently wholesome to be fed to calves."