title: Extended-spectrum and AmpC β-lactamase-producing Escherichia coli in broilers and people living and/or working on broiler farms: prevalence, risk factors and molecular characteristics.
abstract: OBJECTIVE
  The objectives of this study were to: estimate the prevalence of extended-spectrum β-lactamase (ESBL)- and AmpC β-lactamase-producing Escherichia coli carriage among broiler farmers, their family members and employees; identify and quantify risk factors for carriage, with an emphasis on contact with live broilers; and compare isolates from humans and broilers within farms with respect to molecular characteristics to gain insight into transmission routes.
  
  
  METHODS
  A cross-sectional prevalence study was conducted on 50 randomly selected Dutch broiler farms. Cloacal swabs were taken from 20 randomly chosen broilers. Faecal swabs were returned by 141 individuals living and/or working on 47 farms. ESBL/AmpC-producing E. coli were isolated and, for selected isolates, phylogenetic groups, plasmids and sequence types were determined. Questionnaires were used for risk factor analysis.
  
  
  RESULTS
  All sampled farms were positive, with 96.4% positive pooled broiler samples. The human prevalence was 19.1%, with 14.3% and 27.1% among individuals having a low and a high degree of contact with live broilers, respectively. Five pairs of human-broiler isolates had identical genes, plasmid families and E. coli sequence types, showing clonal transmission. Furthermore, similar ESBL/AmpC genes on the same plasmid families in different E. coli sequence types in humans and broilers hinted at horizontal gene transfer.
  
  
  CONCLUSIONS
  The prevalence among people on broiler farms was higher than in previous studies involving patients and the general population. Furthermore, an increased risk of carriage was shown among individuals having a high degree of contact with live broilers. The (relative) contribution of transmission routes that might play a role in the dissemination of ESBL/AmpC-encoding resistance genes to humans on broiler farms should be pursued in future studies.
authors.affiliation: Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands Quantitative Veterinary Epidemiology Group, Wageningen Institute of Animal Sciences (WIAS), Wageningen University, Wageningen, The Netherlands.
authors.forename: P M C
authors.initials: PM
authors.lastname: Huijbers
authors.affiliation: Quantitative Veterinary Epidemiology Group, Wageningen Institute of Animal Sciences (WIAS), Wageningen University, Wageningen, The Netherlands.
authors.forename: E A M
authors.initials: EA
authors.lastname: Graat
authors.affiliation: Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: A P J
authors.initials: AP
authors.lastname: Haenen
authors.affiliation: Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: M G
authors.initials: MG
authors.lastname: van Santen
authors.affiliation: Department of Bacteriology and TSEs, Central Veterinary Institute (CVI) of Wageningen UR, Lelystad, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: van Essen-Zandbergen
authors.affiliation: Department of Bacteriology and TSEs, Central Veterinary Institute (CVI) of Wageningen UR, Lelystad, The Netherlands Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: D J
authors.initials: DJ
authors.lastname: Mevius
authors.affiliation: Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands engeline.van.duijkeren@rivm.nl.
authors.forename: E
authors.initials: E
authors.lastname: van Duijkeren
authors.affiliation: Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: A H A M
authors.initials: AH
authors.lastname: van Hoek
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000383:Agriculture; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D002645:Chickens; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D058885:Multilocus Sequence Typing; D009426:Netherlands; D010802:Phylogeny; D011201:Poultry Diseases / Q000453:epidemiology* / Q000382:microbiology*; D015995:Prevalence; D012307:Risk Factors; D055815:Young Adult; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; C048795:AmpC beta-lactamases; D001618:beta-Lactamases
keywords: ESBLs; MLST; carriage; phylogenetic groups; plasmids