|Edrington, Thomas - Tom|
|Jung, Yong Soo|
|Nisbet, David - Dave|
Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2002
Publication Date: 2/27/2003
Citation: Edrington, T.S., Callaway, T.R., Varey, P.D., Jung, Y.S., Bischoff, K.M., Elder, R.O., Anderson, R.C., Kutter, E., Brabbin, A.D., Nisbet, D.J. Effects of the antibiotic ionophores monensin, lasalocid, laidlomycin propionate and bambermycin on salmonella and E. coli 0157:H7 in vitro. Journal of Applied Microbiology. 2003. v. 94. p. 207-217. Interpretive Summary: Ionophores are antibiotics that improve the growth and performance of young cattle and sheep. The use of ionophores in cattle production is very common. The similar time frame in which ionophore use and food sickness caused by E. coli O157:H7 began has raised concerns. The purpose of the present study was to determine if type or concentration of ionophore has any impact on growth of E. coli and Salmonella in pure and mixed ruminal cultures in the laboratory. Results showed no effect of ionophores on growth rates or colony forming units when added to E. coli or Salmonella grown in pure culture or culture containing mixed ruminal fluid.
Technical Abstract: Escherichia coli O157:H7 and Salmonella are widely recognized as important agents of foodborne disease with worldwide distribution. The use of ionophores in feeding growing ruminants is widespread in the United States and has attracted recent interest due to the apparent temporal relationship between initial ionophore use and the increase in human E. coli O157:H7 cases. Four Salmonella serotypes (Derby, Dublin, Enteriditis, and Typhimurium and two strains of E. coli O157:H7 (ATCC 43895 and FDIU 6058) were incubated in the presence of varying concentrations of ionophores (monensin, lasalocid, laidlomycin propionate, and bambermycin) in pure and mixed ruminal fluid cultures. Bacterial growth rates in pure culture were not affected (P > .10) by ionophores at concentrations as high as 10-times the approximate rumen ionophore concentration under normal feeding regimes. Likewise, ionophores had no effect (P > .10) on Salmonella or E. coli CFU plated from 24 h ruminal fluid incubations. Ionophore treatment decreased (P < .01) the acetate: propionate ratio in ruminal fluid cultures as expected. Ionophores had no effect on the foodborne pathogens Salmonella and E. coli O157:H7 in vitro. Results suggest that ionophore feeding would have little or no impact on Salmonella or E. coli populations in the ruminant.