Field investigations to examine antimicrobial resistance of Enterobacteriaceae from cattle

Does the administration of antimicrobials to animals result in the selection of resistant bacteria? Can those resistant bacteria be transferred to humans and then cause infections that are difficult to treat? These questions have been the subject of debate for more than 40 years (Anon, 1969; Anon, 1998). The UK Government's recent report "Microbial Antibiotic Resistance in Relation to Food Safety" (Anon, 1999a) indicated a need for a coherent strategy aimed at reducing the veterinary usage of antibiotics. Yet, to develop effective management policies, which might limit the frequency of antimicrobial resistance acquisition in bacterial populations, more fundamental field information is required. Researchers from SAC Veterinary Science Division (SAC VSD) have carried out a series of hypothesis-generating field studies to (i) estimate the prevalence of antimicrobial resistance in bovine derived Enterobacteriaceae and (ii) determine which procedures on the farm are associated with increasing prevalence of resistance. This paper describes the studies and provides preliminary findings. Analysis is ongoing and more results will be available by the time of presentation.