Observations on the association of pathogenic Escherichia coli with small intestinal villi of pigs.

Pathogenic Escherichia coli were observed in association with microvilli of piglets experimentally infected with E coli O149:K91,K88a,c, but the bacteria were only rarely observed actually in contact with microvilli. The association of E coli with villi occurred most commonly in the ileum and least commonly in the duodenum: in some pigs, it was only observed in the ileum. The proliferation of pathogenic E coli in the small intestine and their association with villi commonly coexisted, although each phenomenon was also observed independently. It is suggested that the villous association of pathogenic E coli is not a prerequisite for their proliferation.