Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/16/1999
Publication Date: N/A
Technical Abstract: Escherichia coli(EC)O157:H7 and Salmonella typhimurium (ST) DT104 are food borne pathogens of concern to the beef industry. These pathogens can respire anaerobically using nitrate as an electron acceptor. Since most known respiratory nitrate reductases also reduce chlorate (ClO3) to the toxic ion chlorite, we hypothesized that ClO3 may selectively kill EC and salmonellae. In support of this hypothesis, we found that concentrations of EC O157:H7 and ST DT104 were reduced from >= 100,000 colony forming units (CFU) to <= 10 CFU following a 24 hr in vitro incubation in ruminal fluid containing 1.3 mM added ClO3. In contrast, ClO3 had little effect on concentrations of total culturable anaerobes. We report here results from experiments designed to assess the effect of ClO3 to EC in the bovine gut. In order to simultaneously assess the potential toxicity of ClO3 to cattle, we used a large dose of 30 mM sodium ClO3. Experiments were conducted with animals fed and fasted. Concentrations of EC, expressed as log base 10 CFU/g contents, were determined via viable cell count on MacConkey Agar. Whether fasted or not, ruminal EC concentrations declined slightly from per-ClO3 levels by 10 hr post-ClO3 addition (from 3.6 to <= 3.3). In contrast, ruminal EC concentrations from the animals not given ClO3 increased more than 0.4 log CFU/g over the same time period. We observed a greater effect of intraruminal addition of ClO3 on fecal EC concentrations (a decrease of >= 2.54 log CFU/g by 24 hr).