title: Prevalence and subtypes of ciprofloxacin-resistant Campylobacter spp. in commercial poultry flocks before, during, and after treatment with fluoroquinolones.
abstract: Five commercial broiler chicken flocks were treated with either difloxacin or enrofloxacin for a clinically relevant infection, as instructed by a veterinarian. Campylobacters were isolated from individual fecal samples and from samples associated with the broiler environment before, during, and after treatment. Ciprofloxacin-resistant Campylobacter jejuni and/or C. coli strains were detected pretreatment in four flocks, but they constituted a very small proportion of the campylobacters present. When the broilers were treated with a fluoroquinolone, a rapid increase in the proportion of ciprofloxacin-resistant campylobacters was observed. During treatment nearly 100% of campylobacters were resistant, and in some flocks a high proportion of resistant strains persisted for up to 4 weeks after treatment. Prior to treatment a variety of campylobacter subtypes were present. During and after treatment considerable changes in both species and subtype prevalence were observed, but no single fluoroquinolone-resistant clone became dominant. Instead, resistant C. coli strains or a mixture of resistant C. coli and C. jejuni strains became dominant, whereas susceptible C. jejuni strains had usually been dominant prior to treatment. The resistant subtypes which emerged and became dominant were not always the same as those detected pretreatment. The persistence of resistant strains for up to 4 weeks posttreatment has important implications for any strategy designed to avoid the introduction of such strains into the food chain.
authors.affiliation: School of Clinical Veterinary Science, University of Bristol, Langford, United Kingdom.
authors.forename: Tom J
authors.initials: TJ
authors.lastname: Humphrey
authors.forename: Frieda
authors.initials: F
authors.lastname: Jørgensen
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Frost
authors.forename: Haddy
authors.initials: H
authors.lastname: Wadda
authors.forename: Gil
authors.initials: G
authors.lastname: Domingue
authors.forename: Nicola C
authors.initials: NC
authors.lastname: Elviss
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Griggs
authors.forename: Laura J V
authors.initials: LJ
authors.lastname: Piddock
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001434:Bacteriophage Typing; D002167:Campylobacter / Q000145:classification / Q000187:drug effects*; D002169:Campylobacter Infections / Q000188:drug therapy / Q000382:microbiology* / Q000662:veterinary*; D016123:Campylobacter jejuni / Q000145:classification / Q000187:drug effects; D002645:Chickens / Q000382:microbiology*; D002939:Ciprofloxacin / Q000494:pharmacology*; D015169:Colony Count, Microbial; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects; D005243:Feces / Q000382:microbiology; D024841:Fluoroquinolones / Q000627:therapeutic use*; D011201:Poultry Diseases / Q000188:drug therapy / Q000382:microbiology*; D012703:Serotyping; D006113:United Kingdom
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D002939:Ciprofloxacin