title: Antimicrobial resistance in generic Escherichia coli isolated from swine fecal samples in 90 Alberta finishing farms.
abstract: The objective of this study was to determine the prevalence of antimicrobial resistance in generic Escherichia coli isolates obtained from 90 Alberta finisher swine farms. Up to 5 isolates were obtained from each of 269 pooled fecal samples and were classified as susceptible or resistant according to Clinical and Laboratory Standards Institute guidelines. Of the 1322 isolates, 166 (12.6%) were susceptible to all 15 antimicrobials. No resistance to amikacin, ceftiofur, ceftriaxone, or ciprofloxacin, antimicrobials of importance in human medicine, was observed. Relatively low frequencies of resistance were observed to gentamicin (1.1%), amoxicillin/clavulanic acid (0.7%), and cefoxitin (0.7%). Higher frequencies of resistance were observed for tetracycline (78.9%), sulfisoxazole (49.9%), streptomycin (49.6%), ampicillin (30.6%), chloramphenicol (17.6%), kanamycin (10%), and trimethoprim/ sulfamethoxazole (6.4%). Among the isolates resistant to > or = 2 antimicrobial classes, 20.8%, 20.6%, 18.2%, 7.0%, 1.8%, 0.2%, and 0.2% were resistant to 2, 3, 4, 5, 6, 7, and 8 antimicrobials, respectively. The most common multidrug-resistance patterns (resistance to > or = 2 antimicrobial classes) were streptomycin-tetracycline (9.4%), streptomycin-sulfisoxazole-tetracycline (6.2%), and ampicillin-streptomycin-sulfisoxazole-tetracycline (6.1%). More clustering (higher intra-class correlation coefficients) in antimicrobial resistance was observed for isolates at the same visit than for isolates from different visits in the same farm, indicating that sampling more farms, testing fewer isolates per visits, and taking longer periods between visits may be appropriate and more efficient for a better understanding of potential shifts in resistance over time.
authors.affiliation: Department of Population Medicine, University of Guelph, Ontario N1G 2W1. vargac@uoguelph.ca
authors.forename: Csaba
authors.initials: C
authors.lastname: Varga
authors.forename: Andrijana
authors.initials: A
authors.lastname: Rajić
authors.forename: Margaret E
authors.initials: ME
authors.lastname: McFall
authors.forename: Brent P
authors.initials: BP
authors.lastname: Avery
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Reid-Smith
authors.forename: Anne
authors.initials: A
authors.lastname: Deckert
authors.forename: Sylvia L
authors.initials: SL
authors.lastname: Checkley
authors.forename: Scott A
authors.initials: SA
authors.lastname: McEwen
mesh_terms: D000367:Age Factors; D000416:Alberta; D000818:Animals; D000831:Animals, Newborn; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial / Q000662:veterinary; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D005243:Feces / Q000382:microbiology*; D005260:Female; D008297:Male; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D015995:Prevalence; D012307:Risk Factors; D012621:Seasons; D012737:Sex Factors; D013552:Swine; D013553:Swine Diseases / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents