title: Sampling considerations for herd-level measurement of faecal Escherichia coli antimicrobial resistance in finisher pigs.
abstract: The objective of this study was to determine the most efficient means of sampling faeces of finisher pigs for accurate and precise farm-level estimates of antimicrobial resistance among faecal Escherichia coli. Resistance to tetracycline and gentamicin of 8250 isolates of E. coli from 55 finisher pigs on one farm was measured with a hydrophobic grid membrane filter method. The between-pig, within-pen component of variance in resistance was large (97.5%), while between-pen, within-room and between-room components were small (2.5% and 0%, respectively). Using these resistance data, the abilities of two sampling strategies to estimate prevalence were modelled with a Monte Carlo 'bootstrap' procedure. Compositing faecal samples from several pigs before testing produced unbiased and precise estimates of prevalence and is simpler technically than individual animal testing.
authors.affiliation: Department of Population Medicine, University of Guelph, Ontario, Canada.
authors.forename: R H
authors.initials: RH
authors.lastname: Dunlop
authors.forename: S A
authors.initials: SA
authors.lastname: McEwen
authors.forename: A H
authors.initials: AH
authors.lastname: Meek
authors.forename: R M
authors.initials: RM
authors.lastname: Friendship
authors.forename: W D
authors.initials: WD
authors.lastname: Black
authors.forename: R C
authors.initials: RC
authors.lastname: Clarke
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary; D005243:Feces / Q000382:microbiology*; D005260:Female; D005839:Gentamicins / Q000494:pharmacology*; D008297:Male; D008826:Microbial Sensitivity Tests; D011897:Random Allocation; D013048:Specimen Handling / Q000379:methods / Q000662:veterinary; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology; D013752:Tetracycline / Q000494:pharmacology*; D013753:Tetracycline Resistance
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins; D013752:Tetracycline