This study indicates that treating cattle with sodium chlorate reduced E. coli, …

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Biology Articles » Agriculture » Animal Production » Sodium chlorate supplementation reduces E. coli O157:H7 populations in cattle

Abstract

- Sodium chlorate supplementation reduces E. coli O157:H7 populations in cattle

Sodium chlorate supplementation reduces E. coli O157:H7 populations in cattle¹

T. R. Callaway2, R. C. Anderson, K. J. Genovese, T. L. Poole, T. J. Anderson, J. A. Byrd, L. F. Kubena, and D. J. Nisbet

Food and Feed Safety Research Unit, Southern Plains Agricultural Research Center, Agricultural Research Service, USDA, College Station, TX 77845

ABSTRACT

Cattle are a natural reservoir of the food-borne pathogen Escherichia coli O157:H7. Therefore, strategies that reduce E. coli O157:H7 prior to slaughter will reduce human exposures to this virulent pathogen. When bacteria that can anaerobically respire on nitrate (e.g., E. coli) are exposed to chlorate, they die because the intracellular enzyme nitrate reductase converts nitrate to nitrite, but also co-metabolically reduces chlorate to cytotoxic chlorite. Because chlorate is bactericidal only against nitrate reductase-positive bacteria, it has been suggested that chlorate supplementation be used as a strategy to reduce E. coli O157:H7 populations in cattle prior to harvest. Cattle (n = 8) were fed a feedlot-style high-grain diet experimentally infected with three strains of E. coli O157:H7. Cattle were given access to drinking water supplemented with 2.5mMKNO3 and 100mMNaCl (controls; n = 4) or 2.5 mM KNO3 and 100 mM NaClO3 (chloratetreated; n = 4). Sodium chlorate treatment for 24 h reduced the population of all E. coli O157:H7 strains approximately two logs (104 to 102) in the rumen and three logs (106 to 103) in the feces. Chlorate treatment reduced total coliforms and generic E. coli from 106 to 104 in the rumen and by two logs throughout the rest of the gastrointestinal tract (ileum, cecum, colon, and rectum). Chlorate treatment reduced E. coli O157:H7 counts throughout the intestinal tract but did not alter total culturable anaerobic bacterial counts or the ruminal fermentation pattern. Therefore, it appears that chlorate supplementation is a viable potential strategy to reduce E. coli O157:H7 populations in cattle prior to harvest.

Key Words: Escherichia coli O157:H7, Chlorate, Cattle

J. Anim. Sci. 2002. 80:1683–1689.