Enteric infections caused by non-enterotoxigenic Escherichia coli in animals: occurrence and pathogenicity mechanisms. A review.

Not all E. coli that cause diarrhoea in farm animals act by elaborating the classical heat-labile or heat-stable enterotoxins. These newly recognised animal enteropathogenic E. coli (EPEC) attach to and efface the microvilli of the gut epithelium and resemble the well known human EPEC. In rabbits, only this type of E. coli enteritis is known to be important and a similar disease has been shown to occur in cattle also. There is no doubt that adherence factors are important in the pathogenesis of animal EPEC, but they are not well understood when compared with the adhesion of human EPEC, or to the adhesion of animal ETEC. The enteropathogenic effect is probably due to Shiga-like toxin, a cytotoxin that is active on Vero cells and has also been called Verotoxin. A different type of Verotoxin is produced by most serotypes that are associated with post-weaning diarrhoea and oedema disease in pigs. This toxin is suspected to play a role in the pathogenesis of the latter.