Ability of Escherichia coli O157 : H7 isolates to colonize the intestinal tract of conventional adult CD1 mice is transient

In an attempt to improve upon a current mouse model of intestinal colonizat ion by Escherichia coli O157:H7 used in this laboratory for vaccine develop ment, nine clinical isolates of the pathogen were screened for their abilit y to persist in the intestinal tract of conventional adult CD-1 mice. None of the test isolates of E. coli O157:H7 were capable of colonizing these mi ce for a period of more than two weeks. Most of the isolates appeared to be benign for the experimental host, but one isolate was lethal. This virulen ce correlated with the ability of the latter isolate to produce large quant ities of Shiga-like toxin 2 in vitro.