Escherichia coli form part of the natural gastro–intestinal flora of humans and warm-blooded animals. Although most E. coli are harmless commensal organisms, there are many pathogenic strains which can cause a variety of illnesses in humans and animals. These include

• Enteropathogenic E. coli (EPEC)
• Enterotoxigenic E. coli (ETEC)
• Enteroinvasive E. coli (EIEC)
• Enterohaemorrhagic E. coli (EHEC) (including VTEC)
• Enteroaggregative E. coli (EAggEC), Necrotoxigenic E. coli (NTEC)
• Diffusely Adherent E. coli (DAEC)

New modes of transmission and virulence, coupled with a very low infectious dosage, make pathogenic E. coli a major public health issue. Furthermore, there is little doubt that more pathogenic E. coli groups will evolve and be recognised in the future. The research / surveillance / regulatory community must be proactive in recognising and sharing information on emergent strains so that public health issues can be addressed in a timely manner.

Despite considerable research on E. coli O157, there are still areas where a fundamental understanding of these organisms is lacking. Furthermore, technical deficiencies and a lack of harmonisation across disciplines along the food chain and between continents have prevented optimum gain from past and ongoing research. This co-ordination action project will form a durable multidisciplinary network of 35 international research groups working on E. coli O157 and other potentially pathogenic strains and serotypes of E. coli, with the ultimate aim of reducing the burden of related illness.