title: Associations of antimicrobial uses with antimicrobial resistance of fecal Escherichia coli from pigs on 47 farrow-to-finish farms in Ontario and British Columbia.
abstract: This study assessed the associations between antimicrobial use and other management practices in pigs and antimicrobial resistance in generic Escherichia coli recovered from feces of weaner and finisher pigs on 39 purposefully selected farrow-to-finish farms in Ontario and 8 in British Columbia. Antimicrobials (n = 13), most frequently penicillins and tetracycline, wer dministered to different age groups of pigs on study farms through various routes of administration. Logistic regression was used to model risk factors to antimicrobial resistance in fecal E. coli of pigs for the following antimicrobials: ampicillin, apramycin, carbadox, cephalothin, chloramphenicol, kanamycin, neomycin, nitrofurantoin, spectinomycin, streptomycin, sulfamethoxazole tetracycline, and cotrimoxazole (trimethoprim and sulfamethoxazole). Use of antimicrobials in weaner pigs compared with use in finisher pigs was associated with resistance in most models. There was phenotypic evidence of different mechanisms of resistance selection, including direct selection [use of carbadox was associated with carbadox resistance (OR = 6.48)]; cross-resistance [use of spectinomycin was associated with streptomycin resistance (OR = 2.29)]; and possible co-selection [ceftiofu use was associated with tetracycline resistance (OR = 6.12)]. These results provide further evidence that use of antimicrobials in pigs selects for resistance among fecal E. coli within and between classes of antimicrobials.
authors.affiliation: Department of Population Medicine, University of Guelph, Guelph, Ontario N1G 2W1. holy.akwar@gnb.ca
authors.forename: Holy T
authors.initials: HT
authors.lastname: Akwar
authors.forename: Cornelis
authors.initials: C
authors.lastname: Poppe
authors.forename: Jeff
authors.initials: J
authors.lastname: Wilson
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Reid-Smith
authors.forename: Monica
authors.initials: M
authors.lastname: Dyck
authors.forename: Josh
authors.initials: J
authors.lastname: Waddington
authors.forename: Dayue
authors.initials: D
authors.lastname: Shang
authors.forename: Scott A
authors.initials: SA
authors.lastname: McEwen
mesh_terms: D000367:Age Factors; D000821:Animal Feed; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000494:pharmacology; D001955:British Columbia / Q000453:epidemiology; D015169:Colony Count, Microbial / Q000662:veterinary; D004197:Disease Reservoirs / Q000382:microbiology / Q000662:veterinary; D004305:Dose-Response Relationship, Drug; D004333:Drug Administration Routes / Q000662:veterinary; D024881:Drug Resistance, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects*; D005243:Feces / Q000382:microbiology*; D005260:Female; D016015:Logistic Models; D008297:Male; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D009864:Ontario / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors; D013552:Swine / Q000254:growth & development / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents