title: Voluntary ban on cephalosporin use in Danish pig production has effectively reduced extended-spectrum cephalosporinase-producing Escherichia coli in slaughter pigs.
abstract: OBJECTIVE
  To measure the effect of a voluntary ban on cephalosporin usage in the Danish pig production on the prevalence of extended-spectrum cephalosporinase (ESC)-producing Escherichia coli in pigs and pork.
  
  
  METHODS
  Data on cephalosporin consumption were obtained from the VetStat database. For detection of ESC-producing E. coli, three sampling types were included: at slaughter, caecal samples were collected from pigs in 2009 and 2010 (June) before and in two periods (2010 and 2011) after a voluntary ban on cephalosporins was effected (July 2010); at farm level, pools of five stool samples from different pigsties were collected in 2010 and in 2011; and samples from pork were collected randomly at retail stores and outlets from 2009 to 2011. ESC-producing E. coli was isolated after selective enrichment in MacConkey broth with 1 mg/L ceftriaxone. ESC genes were detected using PCR, microtube array and sequencing.
  
  
  RESULTS
  From July 2010 the consumption of cephalosporins approximated zero. The occurrence of ESC-producing E. coli in pigs at slaughter was not significantly different (P=0.7) between 2009 [10.8% (85/786)] and 2010 [11.8% (48/407)], but in 2011 the occurrence [3.6% (28/777)] decreased significantly (P<0.001). A significant decrease (P=0.002) in occurrence of ESC-producing E. coli at pig farm level from 2010 [11% (11/99)] to 2011 (0/78) was also observed. The bla(CTX-M-1) gene was most often detected (63%), but bla(CTX-M-14) and bla(CTX-M-15) were also found. Occurrence in pork was between 1.3% and 0.9%.
  
  
  CONCLUSIONS
  The discontinuation of an already low use of cephalosporins in pig production has significantly reduced the occurrence of ESC-producing E. coli.
authors.affiliation: Research Group of Bacterial Genomics and Antimicrobial Resistance, National Food Institute, Technical University of Denmark, Kemitorvet build. 204, 2800 Lyngby, Denmark. yvoa@food.dtu.dk
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Agersø
authors.forename: Frank M
authors.initials: FM
authors.lastname: Aarestrup
mesh_terms: D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000494:pharmacology; D002353:Carrier State / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary; D002432:Cecum / Q000382:microbiology; D002443:Ceftriaxone / Q000494:pharmacology; D002510:Cephalosporinase / Q000235:genetics / Q000378:metabolism*; D002511:Cephalosporins / Q000008:administration & dosage*; D004269:DNA, Bacterial / Q000235:genetics; D003718:Denmark / Q000453:epidemiology; D004032:Diet / Q000379:methods*; D004926:Escherichia coli / Q000201:enzymology* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D005243:Feces / Q000382:microbiology; D016133:Polymerase Chain Reaction; D015995:Prevalence; D013552:Swine; D018440:beta-Lactam Resistance
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D004269:DNA, Bacterial; D002443:Ceftriaxone; D002510:Cephalosporinase