O157:H7 (commonly abbreviated to E.coli O157): A strain ( q.v.) of the bacterium Escherichia coli. While many strains of E.coli cause no adverse health problems for humans or animals, E.coli O157 is highly virulent and often toxin-producing. It is the predominant cause of verocytotoxin ( q.v.) poisoning in humans, sometimes resulting in haemolytic uraemic syndrome ( q.v) and in extreme cases death. The major livestock reservoirs for this bacteria are cattle and sheep

Escherichia coli; bacteria, often used as host cells