Comparison of the in vitro adhesion of K88, K99, F41 and P987 positive Escherichia coli to intestinal villi of 4- to 5-week-old pigs.

The adhesion of K88ab, K88ac, K88ad, P987, K99, F41 and K99/F41 positive Escherichia coli strains to duodenal, jejunal and ileal villi was studied using an in vitro adhesion assay. The villi were harvested from 4- to 5-week-old pigs. The K88+ strains adhered in large numbers (42 +/- 5 to 81 +/- 4 E. coli/250 microns villous length) to the villi from most pigs and in low to moderate numbers (5 +/- 2 to 24 +/- 7 E. coli/250 microns villous length) or not to villi of some pigs. The K99+ and F41+ strains either adhered in low numbers (1 +/- 1 to 11 +/- 2 E. coli/250 microns villous length) or did not adhere, whereas the P987+ and K99/F41+ strains always adhered in low to moderate numbers (2 +/- 1 to 26 +/- 2 E. coli/250 microns villous length). The number of bacteria adhering to the villi was the highest for the K88ab+ and K88ac+ strains (55 +/- 5 to 81 +/- 4 E. coli/250 microns villous length) and decreasing in the following order: K88ad > P987 > K99/F41 > K99 > F41 (= 1 +/- 1 to 4 +/- 1 E. coli/250 microns villous length). There was no difference in the adhesion of the villi of the different small intestinal segments for the P987+ and F41+ strains. The K99+ strains adhered significantly more to the villi of the caudal half of the small intestine, the K99/F41+ strain to jejunal and ileal and the K88+ strains to jejunal villi in comparison to duodenal ones.