Submitted to: Pig Veterinary Society International Congress Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: February 13, 2006
Publication Date: July 16, 2006
Citation: Anderson, R.C., Harvey, R.B., Poole, T.L., Ramlachan, N., Callaway, T.R., Byrd II, J.A., Edrington, T.S., McReynolds, J.L., Nisbet, D.J. 2006. Comparative susceptibilities of representative enterobacteriaceae and gut commensal bacteria to the active agent of an experimental chlorate product [abstract]. 19th International Pig Veterinary Society Congress. 2:463. Technical Abstract: An experimental chlorate product (ECP) has been developed and shown to effectively control enteropathogen colonization in swine and other food animals. However, aside from nondiscriminatory tests showing a lack of bactericidal activity against total culturable anaerobes, we are aware of no reports testing the susceptibility of specific commensal bacteria to chlorate. The objectives of this study were to determine comparative susceptibilities of representative pathogenic and commensal bacteria to the active agent of ECP. Susceptibilities were determined using the disc diffusion method. Consistent with the proposed mechanism of activity of ECP, chlorate (40 µg) exhibited bactericidal activity solely against anaerobically grown Enterobacteriaceae and Veillonella atypica, bacteria known to possess appreciable respiratory nitrate reductase activity, causing inhibition zones > 10 mm in diameter. In the case of Salmonella serovars Anatum, Enteriditis, inhibitory activity (10 mm zone diameter) was observed with 20 µg chlorate and Salmonella serovar Choleraesuis was susceptible (> 13 mm zone diameter) to 20 and 10 µg chlorate. None of the other tested bacteria were susceptible to 20 and 10 µg chlorate. Our observation that chlorate did not exhibit activity against any of the bacteria when grown aerobically, including those possessing respiratory nitrate reductase activity, is also consistent with the proposed mechanism of activity. Most respiratory nitrate reductases are inducible enzymes that are not expressed in the presence of oxygen. Results provide additional information that chlorate selectively targets bacteria expressing respiratory nitrate reductase activity and baseline evidence pertaining to its effective inhibitory concentration.