Shigatoxinogenic Escherichia coli: Significance as a zoonotic pathogen

Certain strains of Escherichia coli, a bacterium belonging to the physiological gut flora, are able to cause serious clinical diseases in the host organisms due to the production of shiga toxins. Domestic and wild ruminants present the natural reservoir of these shigatoxin producing Escherichia coli (STEC). The animals serve as asymptomatic carriers without signs of disease. Humans get infected via primary contaminated, insufficiently heated or secondary contaminated food. Human infections are characterised by severe diarrhoea, possibly followed by fatal sequeleas like the haemolytic-uraemic syndrom (HUS). Hitherto, there is a lack of knowledge about potential circumstances increasing STEC excretion in animals and about predisposing factors for STEC colonisation on animal and herd level. As shigatoxins are encoded on highly mobile genetic elements, apathogenic strains can turn into pathogenic ones after gentransfer and thus, a freedom of STEC in herds is not feasible at all. Up to now, accurate hygiene management not only in the animal husbandry, but also in the following production steps and a sufficient heat treatment of food provide a basis for the reduction of STEC caused human infections.

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