ABSTRACT
Most #. coli strains are not pathogenic and are part of the normal human and animal gut flora. Enterovirulent #. coli include seven groups believed to be associated with diarrhoea (Griffin and Tauxe, 2001). They are defined based on the presence of known or putative virulence factors including toxin production, adhesion and invasiveness (Sussman, 1997 ; Dupont and Mathewson, 1998). Example types include: attaching and effecing E. coli (AEEC), diffusely adherent#, coli (DAEC), enteroaggregativeE. coli (EAggEC), enteroinvasive#, coli (EIEC), enteropathogenic#. coli (EPEC), enterotoxigenic #. coli (ETEC) and verocytotoxin-producing #. coli (VTEC) (Preston et al., 1997). EPEC have been associated with outbreaks of gastrointestinal illness in nurseries and hospital wards. ETEC is a common cause of infection in children in tropical countries and in travellers (Anonymous, 1994; Dalton et al., 1999). In one outbreak, 47 airline passengers suffered from illness strongly associated with eating garden salad made from iceberg and romaine lettuce, endive, and shredded carrots (Beuchat, 1995). In another outbreak, 78 lodge guests became ill after consuming tossed salad as part of a buffet dinner. The salad contained several ingredients, including onions, carrots, zucchini, peppers, broccoli, mushrooms and tomatoes (Beuchat, 1995).
