Staphylococcus aureus is a common bacterium present on skin and in mucous membranes in 20-30% of healthy people. It may sometimes cause infections in humans, typically local skin and wound infections but occasionally more severe infections in the body. Some strains of this bacterium have, however, developed a resistance to beta-lactam antibiotics which includes penicillins and are used for the treatment of many infections. These are called Meticillin-resistant Staphylococcus aureus (MRSA).
Humans mainly acquire MRSA through direct contact between infected humans or contact with medical devices and equipment. MRSA is especially problematic in hospitals where patients with weakened immune systems are at greater risk of infection than the general public.
A specific MRSA strain (CC398) has been reported to occur in food-producing animals, most often in intensively reared pigs, veal calves and chickens, and has also been found in horses and companion animals. EFSA’s Panel on Biological Hazards found that food may be contaminated by CC398, but it has not been associated with food-borne intoxications. However, in areas where MRSA prevalence in food-producing animals is high, people in contact with live animals are at greater risk of acquiring CC398 than the general population, although infections are rare.