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Reduced Intestinal Colonization Of Adult Beef Cattle By Escherichia Coli O157:H7 Tir Deletion And Nalidixic-Acid-Resistant Mutants Lacking Flagellar Expression, Gustavo Bretschneider, Emil M. Berberov, Rodney A. Moxley

School of Veterinary and Biomedical Sciences: Faculty Publications

The importance of the Escherichia coli O157:H7 translocated intimin receptor (Tir) protein in intestinal colonization and the effect of infection with Tir⁺ strains on protection against subsequent challenge was studied in adult beef cattle. Cattle were orally inoculated (C1) with a Shiga toxin-2⁺+ E. coli O157:H7 strain that was Tir⁺ or Tir^-, and 42 days later were re-challenged (C2) with the nalidixic acid (Nal) ^R parent strain to test whether prior infection had any effect on fecal shedding. During the first 14 days post-C1, the Nal^S wildtype (WT) strain was shed at significantly …