Diarrhoeal disease: current concepts and future challenges. Enteroadherent Escherichia coli: a heterogeneous group of E. coli implicated as diarrhoeal pathogens.

Despite a great expansion in our knowledge of the causative agents of infectious diarrhoea over the past 20 years, a significant proportion of diarrhoeal cases remains undiagnosed. Enteroadherent Escherichia coli are a relatively recently identified group of enteric bacteria which have been implicated as diarrhoeal pathogens. These organisms, defined by their ability to adhere to human epithelial-derived tissue culture cells, have been closely studied over the past 10 years and appear to be quite heterogeneous. This review summarizes our current understanding of enteroadherent E. coli and the recognized subgroups. At least 3 distinct tissue culture cell adherence patterns have been recognized: localized adherence, characteristic of enteropathogenic E. coli, diffuse adherence, and aggregative adherence. Studies examining the epidemiological and pathogenic significance of the latter 2 groups, so-called diffusely adhering E. coli and enteroaggregative E. coli, are discussed in detail.