Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 7/11/2000
Publication Date: 10/3/2002
Citation: NYSTROM,E.A. BOVINE ESCHERICHIA COLI O157:H7 INFECTION MODEL. PHILPOTT, D., EBEL, F., EDITORS. HUMANA PRESS, INC., TOTOWA, NJ. SHIGA TOXIN-PRODUCING ESCHERICHIA COLI: METHODS AND PROTOCOLS. 2002. P. 329-338.
Technical Abstract: Cattle are a major source of enterohemorrhagic Escherichia coli (EHEC) O157:H7 and other Shiga toxin-producing E. coli that cause serious foodborne diseases in humans. Most EHEC-infected cattle are asymptomatic carriers of EHEC. We have developed bovine EHEC infection models to identify the bacterial and host factors that are integral to intestinal colonization and shedding of EHEC by cattle. Although EHEC usually do not cause disease in cattle, experimentally- infected colostrum-deprived, neonatal (< 12-h-old) calves develop diarrhea and enterocolitis by 18 h after inoculation with 10**10 CFU of EHEC bacteria. EHEC-infected calves become colonized with bacteria (i.e., have >/= 10**6 CFU of inoculum bacteria/g of intestinal tissue or feces) and have attaching and effacing lesions in both the small and large intestines. In some calves, the disease induced by EHEC may be fatal. This chapter describes the neonatal calf EHEC infection model we are using to study the mechanisms of EHEC colonization in cattle. The focus is on methods used to infect neonatal calves with EHEC O157:H7, observations for clinical signs of disease, necropsy procedures and collection of samples, bacteriological counts, microscopic examination of tissues, and immunohistochemical detection of O157 antigen in formalin-fixed tissues. The neonatal calf model provides information relevant to colonization of the bovine gastrointestinal tract by EHEC colonize the bovine gastrointestinal tract. This information will facilitate identification of methods for preventing infection of cattle with EHEC, and thus reduce the incidence of EHEC infections in humans.