The Influence of Plasmid-Determined and Other Characteristics of Enteropathogenic Escherichia Coli on Their Ability to Proliferate in the Alimentary Tracts of Piglets, Calves and Lambs

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Abstract
By plasmid manipulation and by other techniques, forms of non-pathogenic and of enteropathogenic Escherichia coli strains were obtained that possessed different combinations of the genes that control the production of enterotoxin (Ent) and of 88, 99, 987P, polysaccharide K and O antigens and the utilisation of raffinose and lactose. Mixtures of forms derived from the same strain, each resistant to a different antibiotic, together with much larger numbers of non-pathogenic E. coli organisms and lactobacilli were then given orally to colostrum-deprived calves and lambs and to colostrum-deprived piglets that were genetically resistant (R) or genetically susceptible (S) to infection with 88+ strains of E. coli. The concentrations that each form subsequently attained in different parts of the alimentary tract of these animals was then determined by performing bacterial counts on culture media containing appropriate antibiotics. By this procedure it was possible to compare the part played by the different bacterial components in colonising the alimentary tract.