title: Integron-containing bacteria in faeces of cattle from different production systems at slaughter.
abstract: OBJECTIVE
  To determine the prevalence and characteristics of integron-containing bacteria in faeces of cattle from grass-fed, lot-fed, or organically produced cattle.
  
  
  RESULTS
  Faecal samples from grass-fed (n = 125), lot-fed (n = 125) and organic (n = 135) cattle were tested for the presence of class 1 and class 2 integrons by using PCR and colony hybridisation. The prevalence of class 1 and class 2 integrase were higher in lot-fed cattle (71% and 62%) than grass-fed cattle (52% and 30%) which in turn were higher than organic cattle (25% and 11%). Isolation rates of integron-containing bacteria were reflective of PCR prevalence results.
  
  
  CONCLUSIONS
  The antimicrobial resistance genes harboured by the integrons differed little across the three systems and were typically to antimicrobials that would rarely be used therapeutically or for growth promotion purposes. The differences in prevalence observed between the systems may be a function of the intensiveness of each system.
  
  
  CONCLUSIONS
  Integron-containing bacteria may be present in all cattle production systems regardless of the amount of antimicrobial use and confirms that the prudent use of antimicrobials is required so that the development of integrons harbouring genes significant to human medicine is avoided.
authors.affiliation: Microbiology Group, Food Science Australia, Cannon Hill, Qld, Australia. robert.barlow@csiro.au
authors.forename: R S
authors.initials: RS
authors.lastname: Barlow
authors.forename: N
authors.initials: N
authors.lastname: Fegan
authors.forename: K S
authors.initials: KS
authors.lastname: Gobius
mesh_terms: D000003:Abattoirs; D000821:Animal Feed; D000818:Animals; D001315:Australia / Q000453:epidemiology; D001419:Bacteria / Q000235:genetics* / Q000302:isolation & purification; D002417:Cattle / Q000382:microbiology*; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005243:Feces / Q000382:microbiology*; D019426:Integrases / Q000235:genetics; D032023:Integrons / Q000235:genetics*; D016133:Polymerase Chain Reaction; D015995:Prevalence; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D019426:Integrases