|Stahl, C - IOWA STATE UNIVERSITY|
|Lincoln, L - IOWA STATE UNIVERSITY|
Submitted to: American Society of Animal Science Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 4, 2004
Publication Date: July 25, 2004
Citation: Callaway, T.R., Stahl, C.H., Edrington, T.S., Genovese, K.J., Lincoln, L.M., Anderson, R.C., Harvey, R.B., Nisbet, D.J. 2004. Colicin E1, N and A treatment inhibits growth of Escherichia coli O157:H7 strains in vitro [abstract]. Journal of Animal Science. 82(Suppl. 1):126. Technical Abstract: Escherichia coli O157:H7 is a highly virulent food-borne pathogen that causes severe human illnesses and inhabits the intestinal tract of ruminants. Although abattoir do an excellent job of controlling the cross-contamination of pathogens, too many human illnesses linked to animal-derived food products still occur. Therefore, researchers have investigated methods to reduce the overall burden of E. coli O157:H7 entering the abattoir within the live animal. Antibiotic treatment has been proposed to reduce E. coli O157:H7 populations in the live animal; however, with the growing worldwide concern over the prophylactic use of antibiotics in food animals, alternative strategies to the use of traditional antibiotics must be explored. Colicins are antimicrobial proteins produced by some E. coli strains that are inhibitory or bactericidal against other E. coli. In the present study, the efficacy of three pore-forming colicins E1, N and A were quantified in vitro against E. coli O157:H7 strains 86-24 and 933. All three colicins reduced the growth of E. coli O157:H7 strains, but the efficacy of each colicin varied between strains. Colicin E1 was most effective against strain 86-24 and 933. Colicin N, while less effective than E1, was very effective against strain 86-24, however, it was unable to produce more than a 50% reduction in growth against strain 933. Colicin A did not show more than 50% of the efficacy of either of the other colicins, even when added to incubations at 10-fold or greater protein concentrations. Colicin E1 was more effective against both strains of E. coli O157:H7 than colicins A and N, and reduced populations of E. coli O157:H7 more than 1000-fold at concentrations less than 5ug/ml. Colicin N reduced populations of strain 86-24, but not 933; and colicin A did not affect the populations of either E. coli O157:H7 strain tested. These potent antimicrobial proteins may potentially provide an effective and environmentally sound pre-harvest strategy to reduce E. coli O157:H7 populations in ruminant animals.