The Maintenance of Resistance

Donald E. Low1 and Gerald D. Wright2 1University of Toronto and 2McMaster University, Toronto, Ontario, Canada and 1,2Canadian Bacterial Diseases Network, Calgary, Alberta, Canada Despite legislation in the United Kingdom (UK) targeted at controlling the use of antimicrobials in food-producing animals, the farming industry commonly uses these drugs therapeutically, prophylactically, and/or for growth promotion of livestock. Drug resistance in foodborne bacterial enteric pathogens is an almost inevitable consequence. In recent years, developed countries have seen significant increases in the occurrence of resistance in Salmonella spp. and Campylobacter spp., and to a lesser extent, in Vero cytotoxin-producing Escherichia coli O157 (VTEC 0157). Developing nations have also noted increases in the occurrence of resistance in Salmonella spp., though they are almost entirely associated with the use of antimicrobials in human medicine. Examples are S. wien and S. typhimurium, both of which have caused numerous outbreaks of serious disease in the hospital and community, over wide geographical areas.