Verocytotoxin-producing Escherichia coli (VTEC).

Escherichia coli O157:H7 and other Verocytotoxin-producing E. coli (VTEC) are zoonotic pathogens associated with food and waterborne illness around the world. E. coli O157:H7 has been implicated in large outbreaks as well as in sporadic cases of haemorrhagic colitis and the sometimes fatal haemolytic uremic syndrome. VTs produced by these bacteria are thought to damage host endothelial cells in small vessels of the intestine, kidney and brain resulting in thrombotic microangiopathy. All VTs have the same subunit structure, glycolipid cell receptor and inhibit protein synthesis. During VTEC infection, it is thought one or more bacterial adhesins initiates colonization and establishes intimate attachment and is responsible for the translocation of a variety of effectors which alter the structure and function of host cells. VTEC are widespread in animals but ruminants are thought to be their natural reservoir. E. coli O157:H7 colonizes the terminal colon of cattle and can be shed in very large numbers by specific herdmates known as "supershedders". Faeces containing these organisms act as a source of contamination for a variety of foods and the environment. Many VTEC control efforts have been investigated along the "farm to fork" continuum including, vaccination of cattle with colonization factors, and the use of novel antimicrobials, such as bacteriocins, chloral hydrate, bacteriophage and substances which disrupt quorum sensing. In addition, many barriers have been developed for use in the slaughter and food processing industry such as steam pasteurization and irradiation. Despite these efforts many scientific, technical and regulatory challenges remain in the control and prevention of VTEC-associated human illness.