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The purpose of this study is identifying the mechanism responsible for increased shedding of
E. coli O157:H7, growth, and virulence factor expression. The hypothesis for this study, is that
changes in diet do influence the expression of NE levels by the endocrine system, and the activation
of the immune system in cattle during stressful versus non-stressful conditions, during various
seasons, which does lead to increased expression of virulence factors and shedding of E. coli during
the peaks seasons.
<P>The stated objectives for this work were to evaluate the influence of diet and stress conditions on the homeostasis of the immune
and endocrine system of cattle. Second, to determine the influence of these factors on
the shedding of E. coli O157:H7, over the course of four seasons (winter, spring, summer,
and fall).
Findings: Pathogenic E.coli 0157:H7 shedding is a major source of concern in the food and cattle industry. Eliminating contamination sources and preventing the transmission of these organisms, is a goal for researchers and cattle and beef producers. This research sheds insight, into why increased shedding may occur during certain times. We demonstrate experimental evidence which suggests that bacterial organisms like pathogenic E. coli O157:H7 can use cattle stress hormones and other cattle-related conditions as a signal to grow more and to become more potent.
<P> This study also tells us that, when cattle are stressed, their health, diet, and body-signals (stress hormones) are communication sources for bacteria. Bacteria use these cattle-related signals as a message, which causes them to grow rapidly and become more powerful, because they find their environment to be more stressful. All of these conditions in the cattle are likely events that can lead pathogenic bacteria, like E. coli O157:H7, to be shed more in greater cattle- stress conditions.