Pathogenesis of Escherichia Coli O157:H7 in Weaned Calves

  • Evelyn A. Dean-Nystrom
  • Brad T. Bosworth
  • Harley W. Moon
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 473)


Cattle are an important reservoir of Shiga toxin-producing Escherichia coli O157:H7 and other enterohemorrhagic E. coli (EHEC) that cause diarrhea, hemorrhagic colitis, and hemorrhagic uremic syndrome in humans. One strategy for reducing human foodborne EHEC infections is to reduce the levels of EHEC in cattle. Bovine O157:H7 infection models will facilitate identification of virulence factors involved in bovine infections. O157:H7 cause severe diarrhea and attaching and effacing (A/E) mucosal lesions in colostrum-deprived neonatal (< 2h) calves. We hypothesized that O157:H7 also cause A/E lesions in older calves, but these were not detected in earlier studies because intestinal levels of O157:H7 were too low (<106 CFU/g of tissue) for detection of focally distributed microscopic lesions. Weaned 3- to 4-month-old calves were fasted 48 h, inoculated via stomach tube with 1010 CFU of O157:H7 or nonpath-ogenic E. coli, necropsied 4d pi and examined histologically. Calves inoculated with O157:H7 had higher intestinal levels of inoculated E. coli than control animals. The rectum was the major site of colonization. A/E lesions were seen in the rectum and cecum of calves with high levels of O157:H7. Weaned calves, like neonatal calves, are susceptible to intestinal damage induced by EHEC O157:H7. The rectum and cecum may be principal sites of EHEC O157:H7 colonization during the carrier-shedder state in cattle.


Hemolytic Uremic Syndrome Stomach Tube Intestinal Damage Neonatal Calf Intestinal Level 
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Copyright information

© Springer Science+Business Media New York 1999

Authors and Affiliations

  • Evelyn A. Dean-Nystrom
    • 1
  • Brad T. Bosworth
    • 1
    • 3
  • Harley W. Moon
    • 2
  1. 1.Enteric Diseases and Food SafetyUSDA Agricultural Research Service National Animal Disease CenterAmesUSA
  2. 2.Veterinary Medical Research Institute College of Veterinary PathologyIowa State UniversityAmesUSA
  3. 3.FranklinUSA

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