Submitted to: Proceedings of Allen D Leman Swine Conference
Publication Type: Abstract Only
Publication Acceptance Date: September 17, 2001
Publication Date: N/A
Technical Abstract: Chlorate has long been known to be bactericidal against nitrate respiring bacteria such as E. coli and Salmonella, but only recently has its use as a preharvest food safety supplement been investigated. However, as with any new microbial intervention strategy it is important to know whether or not potential development and propagation of resistance among target populations may render future treatments ineffective. Earlier work has shown that chlorate resistant E. coli O157:H7 are not as fit in mixed culture and were not recovered from gut contents of experimentally challenged chlorate treated pigs, but information pertaining to chlorate resistance in Salmonella is lacking. Consequently, we determined the frequency of spontaneously generating chlorate resistant Salmonella serovars Typhimurium (NVSL 95-17766) and Chloerasuis (var. kunzendorf 3246pp) in vitro and found that whether grown in pure or mixed culture, the frequency of recovering chlorate resistant Salmonella varied little, ranging from 1.24 x 10e5 to 1.58 x 10e6. Moreover, we were unable to recover chlorate resistant Salmonella from gut contents of pigs experimentally challenged with 10e8 colony forming units of Salmonella Typhimurium and allowed ad libitum access to drinking water containing 15 or 30 mM sodium chlorate (n = 15 pigs per treatment). These results indicate that competition in mixed culture did not increase the rate of spontaneous mutation and suggest that propagation of chlorate resistance among target bacteria is unlikely in vivo.