Rectoanal Junction Colonization of Feedlot Cattle by Escherichia coli O157:H7 and Its Association with Supershedders and Excretion Dynamics

• Published in: Applied and Environmental Microbiology Vol. 73; no. 5; pp. 1563 - 1568
• Main Authors: Cobbold, Rowland N, Hancock, Dale D, Rice, Daniel H, Berg, Janice, Stilborn, Robert, Hovde, Carolyn J, Besser, Thomas E
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.03.2007
• Subjects: Anal Canal - microbiology; Animal Feed; animal pens; Animals; anus; bacterial colonization; Bacteriology; Biological and medical sciences; Cattle; Cattle Diseases - epidemiology; Cattle Diseases - microbiology; Colonization; Colony Count, Microbial; Correlation analysis; E coli; Escherichia coli; Escherichia coli Infections - epidemiology; Escherichia coli Infections - microbiology; Escherichia coli Infections - veterinary; Escherichia coli O157; Escherichia coli O157 - classification; Escherichia coli O157 - genetics; Escherichia coli O157 - growth & development; Escherichia coli O157 - isolation & purification; Excretion; Excretory system; Feces; Feces - microbiology; Feedlots; food chain; food contamination; Fundamental and applied biological sciences. Psychology; Microbiology; population dynamics; Prevalence; Public Health Microbiology; pulsed-field gel electrophoresis; Rectum - microbiology; serotypes; Excretion; Dynamics; Escherichia coli; Bacteria; Livestock; Colonization; Enterobacteriaceae
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.01742-06

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.