Antimicrobial resistance in commensal Escherichia coli isolated from muscle foods as related to the veterinary use of antimicrobial agents in food-producing animals in Austria.

Controversy exists on veterinary drug application in food animal production and the relevance for human health of antimicrobial resistant commensals isolated from food. The aim of this study was to analyze antimicrobial resistance in Escherichia coli isolated from retail meat of various animal species (including wild roe deer) in Austria. Our results were analyzed taking into consideration the current practices of Austrian veterinarians with regard to their use of antibiotic drugs during pig, poultry, and beef production. Resistant isolates were found most often in pork (76%) followed by poultry (63%) and beef (40%). On wild deer carcasses purchased from Austrian hunters only one isolate was found to be resistant. The latter indicates that antimicrobial resistance is not yet an environmental problem in animals living in the wild. The common use of tetracyclines in veterinary medication in various animal species is clearly reflected in the incidence of antimicrobial resistant isolates in commensal E. coli. The intensive use of fluoroquinolones in poultry could explain the high numbers of nalidixic acid resistant isolates found on poultry meat. Our findings partly explain the impact of veterinary drug application on the resistance development of E. coli isolated from meat.