title: The importance of sample size in the determination of a flock-level antimicrobial resistance profile for Escherichia coli in broilers.
abstract: Determining herd- or flock-specific antimicrobial resistance profiles is important to guide therapeutic use of antimicrobials and to assess risk factors for the development and spread of antimicrobial resistance. As such, it is of utmost importance to optimize the sampling strategy for the determination of herd-specific antimicrobial resistance profiles. However, the multitude of prevalences measured at the same time as well as the presence of variation both at the level of the animal and the bacterial population of concern make it impossible to use conventional sample size determination methods. In this article, the use of bootstrapping techniques for sample size determination was explored. In particular, one-stage and two-stage bootstrap samplings were used to determine the optimal number of animals and the optimal number of isolates within one animal. Results show that focus should be on the number of animals sampled rather than on the number of isolates tested within one animal.
authors.affiliation: Veterinary Epidemiology Unit, Department of Obstetrics, Reproduction, and Herd Health, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium. davy.persoons@ugent.be
authors.forename: Davy
authors.initials: D
authors.lastname: Persoons
authors.forename: Kaatje
authors.initials: K
authors.lastname: Bollaerts
authors.forename: Annemieke
authors.initials: A
authors.lastname: Smet
authors.forename: Lieve
authors.initials: L
authors.lastname: Herman
authors.forename: Marc
authors.initials: M
authors.lastname: Heyndrickx
authors.forename: An
authors.initials: A
authors.lastname: Martel
authors.forename: Patrick
authors.initials: P
authors.lastname: Butaye
authors.forename: Boudewijn
authors.initials: B
authors.lastname: Catry
authors.forename: Freddy
authors.initials: F
authors.lastname: Haesebrouck
authors.forename: Jeroen
authors.initials: J
authors.lastname: Dewulf
mesh_terms: D000822:Animal Husbandry / Q000379:methods; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001530:Belgium / Q000453:epidemiology; D002645:Chickens / Q000382:microbiology*; D015169:Colony Count, Microbial; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary; D008826:Microbial Sensitivity Tests; D011201:Poultry Diseases / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D015995:Prevalence; D018401:Sample Size
chemical_list: D000900:Anti-Bacterial Agents