THE EFFECT OF LACTOBACILLUS SPP ON THE ATTACHMENT OF ENTEROTOXIGENIC ESCHERICHIA-COLI TO ISOLATED PORCINE ENTEROCYTES

A total of 43 strains of lactobacilli were isolated from the gastroint estinal tract of piglets at the time of weaning. Isolates, grown on so lid media, were allocated to strongly adherent or non/weakly adherent groups on the basis of numbers attaching to isolated porcine enterocyt es. Strains of Lactobacillus fermentum were disproportionally represen ted amongst the strongly-adherent strains and Lact. acidophilus and La ct. salivarius amongst the non/weakly-adherent group. Lactobacilli sho wed significantly better attachment ability when grown on agar than wh en grown in broth culture. Strongly adherent strains were not found to effect the attachment of enterotoxigenic Escherichia coli to porcine enterocytes, tested under the conditions of exclusion (lactobacilli ad ded to the enterocytes before E. coli), competition (lactobacilli and E. coli added simultaneously) and displacement (E. coli added before l actobacilli). Tests were made with [C-14]-labelled E. coli. Suspension s of bacteria and enterocytes were passed through a filter selected to retain enterocytes but pass free bacterial cells. Counts (dpm) obtain ed from filters after solubilization were taken as a measure of E. col i attachment. Some strains of lactobacilli coaggregated with enterotox igenic E. coli with K88 fimbriae, but not with a K88-negative mutant s train. These were excluded from the competitive exclusion experiments. In the apparent absence of a direct effect on the association of E. c oli with host tissue, removal of potential gut pathogens by aggregatio n could contribute to the probiotic properties ascribed to lactic acid bacteria.