A new strain of methicillin-resistant Staphylococcus aureus, commonly known as MRSA, has been discovered in cows and humans in the United Kingdom and elsewhere in Europe, researchers reported Thursday. The new strain disturbs researchers because it evades one of the most commonly used tests to detect MRSA, which could lead physicians to prescribe the wrong antibiotics to treat the infection. The new strain of the bacterium is still relatively rare and, so far, no deaths have been attributed to it, the team reported in the journal Lancet Infectious Diseases. Its discovery in cows raises a new question about the origin of MRSA outbreaks, however: Are cows a natural reservoir for the infections or are they infected by humans who come into contact with them?
The presence of the bacteria in cows does not present a threat to the food supply because it is killed during the pasteurization process. But the infection can be transmitted to humans who come into close contact with the animals, and these workers can then pass the bacteria into the general population.
Although MRSA infections may be declining in the United States, they still represent a serious healthcare problem, with an estimated 90,000 new infections linked to healthcare facilities each year and about 15,000 deaths, mostly in older people or those with underlying health problems.