Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 9/8/2006
Publication Date: 12/3/2006
Citation: Nystrom, E.A., Pohlenz, J.F., Stoffregen, W.C. 2006. Attachment of shigatoxigenic Escherichia coli O157:H7 to squamous epithelial cells in cattle [abstract]. Research Workers in Animal Diseases Conference Proceedings. p. 103.
Technical Abstract: Shigatoxigenic Escherichia coli (STEC) are commonly found in the gastrointestinal tracts of healthy cattle and spread into the environment by fecal shedding. The terminal rectal mucosa is a prominent colonization site for the human pathogen STEC O157:H7 in cattle. We have necropsied and histologically examined 55 weaned (3-4-mos) calves 4d after inoculation with 1010 CFU of STEC O157:H7 and identified the rectal anal junction (RAJ) as one of the sites where STEC O157:H7 are most likely to be found in experimentally-inoculated calves. Surprisingly, O157+ bacteria bound not only to enterocytes, but also to squamous epithelial cells, in the RAJ. Recently, a rectal anal mucosal swab (RAMS) culture technique was shown to be more sensitive than fecal culture for identifying O157:H7-colonized cattle. We hypothesized that RAMS samples will also be useful for studying STEC O157:H7 adherence to squamous epithelial cells. Examination by immunofluorescence staining showed that RAMS samples contained large numbers of squamous epithelial cells, and that some of the RAMS samples obtained from O157:H7-inoculated calves at 1 to 5d PI contained squamous epithelial cells with adherent O157+ bacteria. O157:H7 bacteria also adhered in vitro to squamous epithelial cells in RAMS samples obtained from non-infected calves. The ability to use easily obtained RAMS samples for in vivo and in vitro STEC adherence studies, as well as for bacterial cultures, will facilitate elucidation of STEC O157:H7 colonization mechanisms and development of intervention strategies for reducing STEC O157:H7 in cattle. Dedicated to the memory of Joachim Pohlenz, June 5, 1936 to January 10, 2006.