title: Prevalence of antimicrobial resistance among Salmonella on midwest and northeast USA dairy farms.
abstract: The objective of this study was to determine the prevalence of antimicrobial resistance among Salmonella isolated from dairy herds in New York, Minnesota, Michigan, and Wisconsin, USA. Serogroup and antimicrobial susceptibility characteristics were determined for Salmonella from cattle and environmental samples collected during August 2000-October 2001 as part of a longitudinal study where 129 herds were visited at 2-month intervals. Salmonella isolates were tested (using a broth microdilution method) for susceptibility to amoxicillin/clavulanic acid, ampicillin, ceftiofur, ceftriaxone, cephalothin, chloramphenicol, ciprofloxacin, gentamicin, kanamycin, nalidixic acid, streptomycin, sulfamethoxazole, tetracycline, and trimethoprim/sulfamethoxazole. Of the 1506 isolates tested for minimum inhibitory concentrations to these 14 antimicrobial agents, 81.2% were pan-susceptible and for most herds (81.6%) the predominant antimicrobial resistance pattern was pan-susceptible. At least 1 Salmonella isolate resistant to 5 or more antimicrobial agents was found on 23.6% of herds. This resistance phenotype was most common among serogroups B and E1 and among samples from calves and farmer-designated sick cows. Resistant samples most frequently exhibited resistance to tetracycline, streptomycin, and/or ampicillin. No samples were resistant to ceftriaxone (though 13 were in the intermediate range), and very few samples were resistant to ciprofloxacin (n=1), nalidixic acid (n=5), or trimethoprim/sulfamethoxazole (n=7).
authors.affiliation: Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, United States.
authors.forename: K A
authors.initials: KA
authors.lastname: Ray
authors.forename: L D
authors.initials: LD
authors.lastname: Warnick
authors.forename: R M
authors.initials: RM
authors.lastname: Mitchell
authors.forename: J B
authors.initials: JB
authors.lastname: Kaneene
authors.forename: P L
authors.initials: PL
authors.lastname: Ruegg
authors.forename: S J
authors.initials: SJ
authors.lastname: Wells
authors.forename: C P
authors.initials: CP
authors.lastname: Fossler
authors.forename: L W
authors.initials: LW
authors.lastname: Halbert
authors.forename: K
authors.initials: K
authors.lastname: May
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy* / Q000382:microbiology; D015169:Colony Count, Microbial / Q000662:veterinary; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D012475:Salmonella / Q000145:classification / Q000187:drug effects*; D012481:Salmonella Infections, Animal / Q000188:drug therapy*; D012703:Serotyping / Q000662:veterinary; D014481:United States
chemical_list: D000900:Anti-Bacterial Agents