New strain of MRSA superbug found in cows

New strain of MRSAsuperbug found in cows A new strain of the MRSA "superbug" hasbeen found in British cows and isbelieved to be infecting humans.Environmental campaigners say the newstrain has emerged because of the over-useof antibiotics by dairy farmers.Dr Mark Holmes of Cambridge University,who led the research, said this was a"credible hypothesis".The researchers, writing in the LancetInfectious Diseases Journal, say there is noadditional health risk from eating milk anddairy products.'Financial pressure'MRSA, or methicillin-resistantStaphylococcus aureus, is a drug-resistantform of a usually harmless bacterium whichcan be deadly when it infects wounds.The 35 or so strains of antibiotic-resistantsuperbugs are genetically fairly similar.However, this new variety is very differentand it is thought that it might have firstemerged from cows.Its discoverers have dubbed it "New MRSA"Antibiotics are widely used by dairy farmersto treat cows with mastitis. However over-use means some bacteria become resistantand difficult to treat if humans becomeinfected.Dr Holmes said the problem might beexacerbated by financial pressures on diaryfarmers."If you drive your cows harder to producemore milk you get more mastitis," he toldreporters at a news conference.The Soil Association has called for acomplete ban on routine use of antibioticsin farming.Soil Association director Helen Browningsaid: "Dairy systems are becoming evermore antibiotic-dependent. We need to getfarmers off this treadmill, even if that meansthat milk has to cost a few pennies more".National Farmers' Union chief dairy adviserRob Newberry said the health and welfare ofcows were of "paramount importance" toBritish dairy farmers."In the interests of human and animalhealth, and animal welfare, it is importantthat veterinary medicines are administeredas little as possible but as much asnecessary," he said."Any antibiotic or veterinary medicine beingadministered to a food producing animalhas strict conditions of use, including milkand meat withdrawal times, and in general,under European law, would only beavailable under prescription."Dr Holmes and his colleague Dr LauraGarcia-Alvarez discovered the new strainwhile studying a bacterium known to causemastitis in cows.They found that, like other MRSA strains, itwas resistant to the most commonly usedantibiotics. However, the bug was found tobe genetically very different.Subsequent research showed that the strainwas also present in humans.Dr Garcia-Alvarez says that finding a newstrain in both in humans and cows is "veryworrying"."Workers on dairy farms are at higher riskof carrying MRSA but we don't yet know ifthis translates to a higher risk [of thembecoming ill]," she said.'Very low risk'Dr Holmes said very few people had beeninfected with the new strain, probably fewerthan 100 a year in the UK. "But it doesappear that the numbers are rising," hesays.The Health Protection Agency said the riskof becoming infected with the new strainwas "very low".Dr Holmes and Dr Garcia-Alvarez will nowinvestigate the prevalence of the new strainand whether it is more or less harmful thancurrent strains.They also plan to conduct studies on farmsto look for more MRSA strains of this typeand explore any potential risks to farmworkers.MRSA is often found in hospitals and waslinked to 1,593 deaths in 2007.Since then the number of suspected fatalcases has fallen dramatically. There were1,290 in 2008 and 781 in 2009.A Department of Health spokesman said:"From the available evidence, weunderstand this new form of MRSA is rare inthe UK and is not causing infections inhumans."However, our expert committee, ARHAI,will be reviewing this issue at their nextmeeting and will consider potential medical,veterinary and food safety issues."A Food Standards Agency spokesman saidthe study did not provide direct evidencethat humans were being infected with MRSAfrom cattle."The risk of contracting this new strain ofMRSA through drinking milk is extremely lowbecause the vast majority of cows' milk ispasteurised and the pasteurisation processdestroys all types of MRSA," he added. New strain of MRSA superbug found in cows