Rectoanal junction colonization of feedlot cattle by Escherichia coli O157:H7 and its association with supershedders and excretion dynamics

Appl Environ Microbiol. 2007 Mar;73(5):1563-8. doi: 10.1128/AEM.01742-06. Epub 2007 Jan 12.

Abstract

Feedlot cattle were observed for fecal excretion of and rectoanal junction (RAJ) colonization with Escherichia coli O157:H7 to identify potential "supershedders." RAJ colonization and fecal excretion prevalences were correlated, and E. coli O157:H7 prevalences and counts were significantly greater for RAJ samples. Based on a comparison of RAJ and fecal ratios of E. coli O157:H7/E. coli counts, the RAJ appears to be preferentially colonized by the O157:H7 serotype. Five supershedders were identified based on persistent colonization with high concentrations of E. coli O157:H7. Cattle copenned with supershedders had significantly greater mean pen E. coli O157:H7 RAJ and fecal prevalences than noncopenned cattle. Cumulative fecal E. coli O157:H7 excretion was also significantly higher for pens housing a supershedder. E. coli O157:H7/E. coli count ratios were higher for supershedders than for other cattle, indicating greater proportional colonization. Pulsed-field gel electrophoresis analysis demonstrated that isolates from supershedders and copenned cattle were highly related. Cattle that remained negative for E. coli O157:H7 throughout sampling were five times more likely to have been in a pen that did not house a supershedder. The data from this study support an association between levels of fecal excretion of E. coli O157:H7 and RAJ colonization in pens of feedlot cattle and suggest that the presence of supershedders influences group-level excretion parameters. An improved understanding of individual and population transmission dynamics of E. coli O157:H7 can be used to develop preslaughter- and slaughter-level interventions that reduce contamination of the food chain.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anal Canal / microbiology*
  • Animal Feed
  • Animals
  • Cattle
  • Cattle Diseases / epidemiology*
  • Cattle Diseases / microbiology
  • Colony Count, Microbial
  • Escherichia coli Infections / epidemiology
  • Escherichia coli Infections / microbiology
  • Escherichia coli Infections / veterinary*
  • Escherichia coli O157 / classification
  • Escherichia coli O157 / genetics
  • Escherichia coli O157 / growth & development*
  • Escherichia coli O157 / isolation & purification
  • Feces / microbiology*
  • Prevalence
  • Rectum / microbiology*