|Jung, Yong Soo|
|Mcreynolds, Jack - TX A&M UNIVERSITY|
Submitted to: Small Ruminant Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 15, 2003
Publication Date: June 20, 2003
Citation: EDRINGTON, T.S., CALLAWAY, T.R., ANDERSON, R.C., GENOVESE, K.J., JUNG, Y., MCREYNOLDS, J., BISCHOFF, K.M., NISBET, D.J. REDUCTION OF E. COLI O157:H7 POPULATIONS IN SHEEP BY SUPPLEMENTATION OF AN EXPERIMENTAL SODIUM CHLORATE PRODUCT. SMALL RUMINANT RESEARCH. 2003. v. 49. p. 173-181. Interpretive Summary: Cattle and sheep are naturally infected with E. coli O157:H7, a bacteria that causes food sickness in humans. Chlorate is a compound that is toxic to certain bacteria such as E. coli O157:H7. We investigated the ability of an experimental chlorate compound to decrease populations of E. coli O157:H7, particularly in the lower intestine in experimentally infected sheep. Results showed that feeding chlorate 24 hours prior to slaughter reduced E. coli O157:H7 shedding in the feces. Furthermore, chlorate decreased populations of E. coli O157:H7 and generic E. coli in gut contents from the lower gastrointestinal tract. These findings support the use of chlorate as a tool to reduce carcass contamination and improve food safety
Technical Abstract: Ruminant animals are naturally infected with the pathogen E. coli O157:H7, annually responsible for numerous meat recalls, foodborne illnesses, and deaths. Escherichia coli is equipped with the enzyme nitrate reductase which not only enables this bacteria to respire anaerobically, but it also converts chlorate to the toxic metabolite chlorite. This enzyme system is particular to only a few intestinal bacteria, therefore the vast majority are not affected by chlorate. Sodium chlorate has been shown to effectively decrease foodborne pathogens in several livestock species, including ruminants. However, because infection and proliferation of E. coli occurs primarily in the lower intestine, there is interest in "by-passing" the rumen and thereby delivering chlorate directly to the largest population of pathogens. The objective of the current study was to evaluate the ability of an experimental chlorate impregnated zeolite product (ECP), designed to by-pass the rumen, on reducing fecal shedding and gut concentrations of E. coli O157:H7. Twenty cross-bred mature ewes were adapted to a high grain ration and experimentally inoculated with E. coli O157:H7. Thirty-six hours following inoculation, sheep received in their feed one of the following ECP treatments: 1) Control (CON), no chlorate; 2) 1X (LOW); 3) 2X (MED); and 4) 4X (HIGH) where X = 1.1 g chlorate ion equivalents/kg BW (5 sheep per treatment). Fecal samples were collected every twelve hours following inoculation and 24 hours following the feeding of chlorate. All animals were euthanized and tissue samples and their respective contents collected from the rumen, cecum, and rectum. The MED and HIGH chlorate treatments significantly reduced fecal shedding of E. coli O157:H7 compared to the CON treatment [1.53, 1.11, and 3.89 CFU/g feces (log10), respectively]. Ruminal contents were similar among treatments while chlorate tended to decrease (P = 0.08) and reduced (P < 0.05) E. coli O157:H7 populations in the cecum and rectum, respectively. Populations of generic E. coli in the cecal contents were numerically lower (P = 0.11) in the LOW treatment and tended to decrease (P = .06) in the MED and HIGH chlorate treatments, respectively. Fermentation profiles through the gastrointestinal tract were unaffected as indicated by slight, but not significant, changes in VFA profiles in sheep fed chlorate. Results from this study indicate that chlorate can be an effective method to decrease E. coli O157:H7 populations in ruminant animals prior to slaughter.