Submitted to: Research in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 11, 2001
Publication Date: January 2, 2002
Interpretive Summary: Escherichia coli are bacteria of importance to the swine industry because they cause economic losses due to disease and also compromise food safety. One particular strain of E. coli, referred to as E. coli O157:H7, causes a very severe food poisoning that can be fatal to young children and the elderly. This strain has recently been found to inhabit the gut of pigs. Escherichia coli possess a particular enzyme that converts chlorate to chlorite inside the bacteria, and the chlorite kills the pathogenic bacteria. However most of the beneficial bacteria in the gut do not possess this enzyme, so chlorate does not kill them. In laboratory experiments we found that giving pigs chlorate decreased the numbers of E. coli 0157:H7 in pigs infected with this pathogenic bacteria by more than 50,000 fold compared to pigs not given the chlorate that were also infected with this pathogen. The numbers of beneficial bacteria in the gut did not change. These results demonstrate that feeding pigs chlorate may be a way to reduce E. coli 0157:H7 concentrations in the pig gut immediately prior to slaughter, which will help farmers and packing plant operators produce safer meat.
Technical Abstract: Strategies are sought to reduce Escherichia coli O157:H7 (E.C.) concentrations in food producing animals. Because E. coli possess respiratory nitrate reductase activity, which also reduces chlorate to cytotoxic chlorite, we tested and found that oral sodium chlorate administration reduced gut concentrations of (E.C.) in weaned pigs that had been experimentally infected at 26 to 29 days of age. The mean log10 CFU of E.C./g gut content (+/- SD) in placebo and chlorate treated pigs respectively were as follow; ileal, 4.03 +/- 2.10 vs 1.56 +/- 0.69; cecal, 3.82 +/- 0.75 vs. 2.65 +/- 1.20; colonic, 4.42 +/- 0.79 vs 3.05 +/- 1.19; and rectal, 4.03 +/- 0.48 vs. 3.0 +/- 0.91. Gut contents in chlorate treated pigs were significantly (P< .05) reduced compared to placebos in all cases. Similar treatment with 200 mM chlorate only marginally increased the bactericidal effect of chlorate against E.C.