title: Spread of extended spectrum cephalosporinase-producing Escherichia coli clones and plasmids from parent animals to broilers and to broiler meat in a production without use of cephalosporins.
abstract: OBJECTIVE
  This study investigated the occurrence of extended spectrum cephalosporinase (ESC)-producing Escherichia coli in a broiler production with no cephalosporin use and a low use of antimicrobials in general. Furthermore, it investigated whether the current consumption of aminopenicillins selects for ESC-producing E. coli and whether certain clones or plasmids spread from imported parent flocks to the meat.
  
  
  METHODS
  ESC-producing E. coli was isolated using MacConkey broth with 1 mg/L of ceftriaxone. ESC genes were identified using polymerase chain reaction and sequencing. Isolates with blaCMY-2 were subtyped by pulsed-field gel electrophoresis (PFGE), phylotyping, and antimicrobial susceptibility testing. Selected isolates were used as donors in filter-mating experiments, multilocus sequence typing (MLST), and plasmid replicons were typed. Aminopenicillin use at the farm (not flock) level was obtained from VetStat, a database for mandatory registration of veterinary prescriptions in Denmark.
  
  
  RESULTS
  ESC-producing E. coli occurred in 93% (27/29) of broiler parent farms in 2011, 27% (53/197) of broiler flocks in 2010, and 3.3% (4/121) of Danish retail broiler meat in 2009 and 8.6% (16/187) in 2010. The ESC producing E. coli contained blaCMY-2, blaSHV-2 or blaCTX-M-1. Isolates with blaCMY-2 represented 35 PFGE groups. One group dominated (39 isolates) and included isolates with indistinguishable PFGE patterns from parents, broilers, and meat. Most blaCMY-2 isolates were susceptible to non-β-lactams, and blaCMY-2 was mostly present on horizontally transferable incI1 or incK plasmids. Phylogroup D was most common and E. coli MLST types previously found in humans were observed. Broiler farms with registered aminopenicillin use had significantly higher occurrence of ESC E. coli.
  
  
  CONCLUSIONS
  ESC-producing E. coli from flocks of imported broiler parents spread clonally and horizontally to broiler meat (including potentially human pathogenic types) even in a country with no cephalosporin use. Use of aminopenicillins may influence the persistence of ESC-producing E. coli in the broiler production, but other factors should be investigated.
authors: 1 Research Group of Bacterial Genomics and Antimicrobial Resistance, National Food Institute, Technical University of Denmark , Lyngby, Denmark .
authors: Yvonne
authors: Y
authors: Agersø
authors: Jacob Dyring
authors: JD
authors: Jensen
authors: Henrik
authors: H
authors: Hasman
authors: Karl
authors: K
authors: Pedersen
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques / Q000662:veterinary; D002510:Cephalosporinase / Q000235:genetics* / Q000378:metabolism; D002511:Cephalosporins / Q000494:pharmacology; D002645:Chickens / Q000382:microbiology*; D003718:Denmark / Q000453:epidemiology; D016521:Electrophoresis, Gel, Pulsed-Field / Q000662:veterinary; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000635:transmission; D029968:Escherichia coli Proteins / Q000235:genetics; D005517:Foodborne Diseases / Q000453:epidemiology / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D058885:Multilocus Sequence Typing / Q000662:veterinary; D010957:Plasmids / Q000235:genetics; D011200:Poultry / Q000382:microbiology*; D011201:Poultry Diseases / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D001618:beta-Lactamases / Q000235:genetics; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D029968:Escherichia coli Proteins; D047090:beta-Lactams; D002510:Cephalosporinase; D001618:beta-Lactamases