Role of non-O157 VTEC

Non-O157 VTEC are typical Escherichia coli that differ only in their abilit y to produce verocytotoxins (VT). The transmission of VTEC is discussed in relation to the transmission of commensal E. coli. The emergence over the l ast few decades of a great variety of VTEC serotypes from healthy and disea sed humans and animals is described. Particular attention is given to the d istribution of the more important serogroups pathogenic for humans that hav e been described from around the world, particularly serogroups O26, O111, O128 and O103. The possible role of ruminants as reservoirs is discussed. T he problems of laboratory diagnosis of non-O157 VTEC are considered and var ious laboratory methods are assessed. Evidence is presented that the partic ular E. coli serotypes now known to be VTEC were present in humans and anim als many years ago, but have acquired the ability to produce VT and probabl y other virulence factors. Finally, predictions are made of the possible in crease in problems associated with these emerging pathogens.