The impact of antimicrobial use regulations on antimicrobial resistance among Salmonella isolates from bovine samples submitted to a veterinary diagnostic laboratory in Central New York

The US Food and Drug Administration (FDA) has imposed restrictions on antimicrobial usage in food-producing animals, including the extra-label use of third-generation cephalosporins. However, the impact of these restrictions on the antimicrobial resistance status of important pathogens like Salmonella remains unclear. A study analyzed veterinary diagnostic laboratory data on 2413 Salmonella isolates from submitted bovine samples and found that the 2012 AMU restriction was associated with a decrease in resistance to chlortetracycline, oxytetracycline, and neomycin. The 2017 AMU restriction also decreased resistance to florfenicol.