Date Published: February 7, 2018
Publisher: Public Library of Science
Author(s): Wendy Beauvais, Elena V. Gart, Melissa Bean, Anthony Blanco, Jennifer Wilsey, Kallie McWhinney, Laura Bryan, Mary Krath, Ching-Yuan Yang, Diego Manriquez Alvarez, Sushil Paudyal, Kelsey Bryan, Samantha Stewart, Peter W. Cook, Glenn Lahodny, Karina Baumgarten, Raju Gautam, Kendra Nightingale, Sara D. Lawhon, Pablo Pinedo, Renata Ivanek, Raymond Schuch.
Escherichia coli O157:H7 fecal shedding in feedlot cattle is common and is a public health concern due to the risk of foodborne transmission that can result in severe, or even fatal, disease in people. Despite a large body of research, few practical and cost-effective farm-level interventions have been identified. In this study, a randomized controlled trial was conducted to assess the effect of reducing the level of water in automatically refilling water-troughs on fecal shedding of E. coli O157:H7 in feedlot cattle. Pens in a feedlot in the Texas Panhandle were randomly allocated as control (total number: 17) or intervention (total number: 18) pens. Fecal samples (2,759 in total) were collected both at baseline and three weeks after the intervention, and tested for the presence of E. coli O157:H7 using immunomagnetic bead separation and selective culture. There was a strong statistical association between sampling date and the likelihood of a fecal sample testing positive for E. coli O157:H7. Pen was also a strong predictor of fecal prevalence. Despite accounting for this high level of clustering, a statistically significant association between reduced water levels in the trough and increased prevalence of E. coli O157:H7 in the feces was observed (Odds Ratio = 1.6; 95% Confidence Interval: 1.2–2.0; Likelihood Ratio Test: p = 0.02). This is the first time that such an association has been reported, and suggests that increasing water-trough levels may be effective in reducing shedding of E. coli O157:H7 in cattle feces, although further work would be needed to test this hypothesis. Controlling E. coli O157:H7 fecal shedding at the pre-harvest level may lead to a reduced burden of human foodborne illness attributed to this pathogen in beef.
Escherichia coli O157:H7 is the predominant serotype representing the Shiga-toxin producing E. coli group associated with human disease. It was first identified as a pathogen in 1982 during an outbreak investigation of hemorrhagic colitis . Human infections caused by E. coli O157:H7 result in clinical syndromes ranging from asymptomatic to severe . A few individuals may develop potentially fatal complications such as hemolytic uremic syndrome . A chronic renal sequela may persist among those that survive .
This intervention trial provided evidence that decreasing the level of water in troughs in feedlot pens that are already contaminated with E. coli O157:H7 may modestly increase the proportion of fecal pats that are positive for E. coli O157:H7. To our knowledge, this is the first time that decreasing water levels in troughs has been shown to be associated with an increased risk of E. coli O157:H7 fecal shedding, and the result was surprising given that previous modeling suggested that the effect would be in the opposite direction [24,31].