FRIDAY, June 3 (HealthDay News) -- A new strain of the antibiotic-resistant bacteria methicillin-resistant Staphylococcus aureus(MRSA) has been detected in cows' milk in the United Kingdom and Denmark.

Dr. Mark A. Holmes, of the department of veterinary medicine at the University of Cambridge in England, and his colleagues warned that this new variant, which is genetically different than existing MRSA strains, could go undetected by typical testing techniques.

Common in hospitals and nursing homes, MRSA can cause serious illness or even death. The new strain of MRSA identified in cows' milk is also associated with disease in humans, according to the report published in the June 2 online edition of The Lancet Infectious Diseases.

Although the pasteurization of milk would prevent any risk of infection through the food chain, the investigators noted that more research is needed to determine if people who come into close contact with cattle are at greater risk because the study also found indirect evidence that cows could be an important source of this new strain of MRSA infection in humans.

The researchers also warned that the new strain of MRSA could be wrongly diagnosed as methicillin-susceptible, leading to prescriptions for the wrong antibiotics.

More information

The U.S. National Institutes of Health offers more detailed information on MRSA.