E. Increased carriage and dissemination
Acquisition of resistant bacteria from farm animals has been shown to occur either via ingestion of foods of animal origin20 or via direct contact with infected animals21, 22. Because of their survival advantage, resistant bacteria may remain viable for longer periods in the environment and in animal reservoirs where they can eventually be transmitted to humans.
Methicillin-resistant Staphylococcus Aureus (MRSA)
MRSA was first reported in 1961, and emerged as a sporadic problem in US hospitals. By the 1990s, MRSA was recognized as a serious worldwide nosocomial (hospital-acquired) infection. MRSA strains are resistant to beta-lactam antibiotics, including those that are not affected by penicillinase. The resistance is mediated by a mecA gene which codes for a penicillin-binding protein (PBP2a) that has low affinity for beta-lactam antibiotics. In the last few years, animals have been implicated in the maintenance, spread and transmission of some types of MRSA among humans. There is evidence that transmission of MRSA strains can occur from animals to humans, and vice-versa. MRSA has been found in humans closely associated with carrier animals; among pet owners23, veterinarians and veterinary personnel24, 25, 26 as well as pig and cattle farmers27, 28. Studies identified both livestock and companion animals as potential sources of MRSA for humans, and close contact with these animals was identified as a risk factor for their carriage in people.