Escherichia coli (E.coli) are bacteria commonly found in the gut of both people and animals. Although many types of E. coli are harmless, infection with Shiga-toxigenic strains of E. coli such as E. coli O111 and E. coli O157 can cause bloody diarrhoea. Infection with Shiga-toxigenic E. Coli can also sometimes lead to haemolytic uraemic syndrome, a condition characterised by kidney failure, bleeding and anaemia which can sometimes be fatal. Infection usually results from consuming contaminated food or water or from contact with infected animals or people.
A letter published online on 29 October in the journal Nature, describes how subtilase cytotoxin, an AB5 type toxin produced by Shiga-toxigenic E. coli, preferentially targets cells expressing glycans terminating in N-glycolylneuraminic acid (Neu5Gc). What is remarkable is that humans are not able to produce Neu5Gc, and so should be resistant to the effects of the toxin. It now seems that red meat and dairy products contain high levels of Neu5Gc which is absorbed into human tissues, including the surface of cells lining the intestines and blood vessels. This means that food contaminated with Shiga-toxigenic E. Coli strains can also provide a ready source of the molecular target for the toxin.
The research emphasizes the need to eat only well cooked meat and pasteurized dairy products, since both processes destroy any contaminating bacteria.