|Rosenkrans, Jr, C - UNIV OF ARKANSAS|
|Flores, R - UNIV OF ARKANSAS|
Submitted to: International Neotyphodium Grass Interactions
Publication Type: Proceedings
Publication Acceptance Date: March 14, 2004
Publication Date: May 23, 2004
Citation: Looper, M.L., Edrington, T.S., Rosenkrans, Jr, C.F., Schultz, C.L., Callaway, T.R., Aiken, G.E., Flores, R., Brauer, D.K. 2004. Effects of the ergot alkaloids dihydroergotamine, ergonovine, and ergotamine on growth of escherichia coli o157:h7 and salmonella in vitro. International Neotyphodium Grass Interactions. #503. Technical Abstract: A recent report demonstrated that the shedding of E. coli 0157:H7 in feces of calves was lower when grazing endophyte-infected tall fescue. A series of experiments were conducted to evaluate the effects of ergot alkaloids (dihydroergotamine, ergonovine, and ergotamine) on E. coli O157:H7 and Salmonella in both pure and mixed ruminal fluid culture. Alkaloids were added to solutions of E. coli O157:H7 strains 933 and 6058 and Salmonella serotypes Montevideo and Mbandaka. Growth rates and colony forming units of pathogenic bacteria were measured. No differences (P > 0.10) were found in growth rates in pure culture for either strain of E. coli O157:H7 when comparing increasing concentrations of the same ergot alkaloid or when comparing different ergot alkaloids. Similarly, the type of ergot alkaloid or ergot alkaloid concentration had no effect (P > 0.10) on growth rate of the two Salmonella serotypes examined. Increasing ergot alkaloid concentrations had no effect (P > 0.10) on CFUs for E. coli O157:H7 strain 933 and 6058 after incubation in mixed ruminal fluid for 24 h. Likewise, no differences (P > 0.10) were observed when different ergot alkaloids were compared. Colony forming units for Salmonella serotypes were unaffected (P > 0.10) by ergot alkaloid concentration or type. There was minimal, if any, affect on the growth of E. coli O157:H7 and Salmonella when exposed to dihydroergotamine, ergonovine, and ergotamine. Other factors such as different ergot alkaloids (i.e., ergovaline), exposure to a combination of alkaloids, characteristics of the grazed forage, or management strategies may influence fecal shedding of Escherichia coli O157:H7 or Salmonella in cattle grazing endophyte-infected tall fescue.