The Role of Super-shedders in Determining Feedlot Pen Prevalence of E. coli  O157:H7

This research confirmed the role of super-shedders cattle in the transmission of E. coli O157:H7 to other cattle in a feedlot environment. Removing a super-shedder from a pen resulted in a decrease in shedding and/or pen prevalence; however the effect was not statistically significant. The addition of a super-shedder to a naïve pen did lead to a statistically significant increase in shedding and prevalence.

Funded in part by The Beef Checkoff

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Objectives

To determine if impact of super shedders in a feedlot pen: 1) if removal of a super-shedder from a feedlot pen results in a reduction in the prevalence, mean count and duration of excretion of E. coli O157:H7 by other cattle in that pen; 2) the addition of a super-shedder to a feedlot pen results in an increase in the prevalence, mean count and duration of excretion of E. coli O157:H7 by other cattle in that pen; 3) transmission of E. coli O157:H7 from super-shedder cattle to in-contact cattle (i.e. pen-mates) using genetic similarity profiling; 4) association between presence of a super-shedder in a pen and the prevalence and identity of E. coli O157:H7 in the pen environment.

Conclusions

Certain cattle within feedlots are colonized by E. coli O157:H7 more frequently, persistently and in greater numbers than other cattle. These “super-shedders” appear to influence the degree of E. coli O157:H7 colonization of other cattle in their pens. When super-shedders are moved to pens with low levels of E. coli O157:H7 activity, the prevalence and persistence of E. coli O157:H7 colonization increases among other cattle in that pen. Similarly, levels of environmental contamination appear to increase as well.  Presuming these effects can result in greater levels of general E. coli O157:H7 carriage, excretion and hide contamination, this represents a risk for greater introduction of E. coli O157:H7 into the slaughterhouse. Interventions designed to identify and negate the effects of super-shedders at strategic points in beef production may help mitigate the food safety risk of E. coli O157:H7. The site of E. coli O157:H7 colonization in cattle appears to be the recto-anal junction. An improved knowledge of how E. coli O157:H7 specifically reside at this site and become excreted in feces will also allow development of interventions designed to reduce E. coli O157:H7 carriage and transmission to other cattle or the food chain.

Deliverable

This study demonstrated that super-shedders influenced the degree of E. coli O157:H7 colonization of other cattle in their pens.  Interventions targeted at super-shedders may reduce the prevalence of transmission and E. coli O157:H7 colonization to other cattle within the same feedlot pen.