The emergence and spread of antibiotic resistance in food-borne bacteria.
Since the early 1990s there has been a dramatic increase in resistance to antimicrobial drugs in Salmonella enterica and Campylobacter spp., and to a lesser extent in Vero cytotoxin-producing Escherichia coli O157 from cases of human infection in developed countries. For S. Typhimurium a particularly important aspect of this increase has been the widespread dissemination of a multiply drug-resistant (MR) strain of definitive phage type (DT) 104 in food animals since the early 1990s. The use of antimicrobials for prophylaxis in food producing animals has been an important factor in the emergence of strains with resistance to certain antimicrobials. It is hoped that recently introduced Codes of Practice for the prophylactic use of antimicrobials in food animals will result in a decline in the occurrence of drug resistant strains in the food chain.