Enteroaggregative Escherichia Coli, A New Diarrheal Agent

Abstract

The ability of Escherichia coli strains to adhere to HEp-2 cells in tissue culture correlates with their capacity to cause diarrhea. Three distinct patterns of adherence have been described: localized, diffuse and aggregative (1). Localized adherence (LA) is characteristic of enteropathogenic E. coli of classical infant diarrhea O:H serotypes (2). This property requires the presence of EPEC Adherence Factor (EAF) genes which are located on a plasmid (2, 4, 5). Several recent epidemiological studies have clearly demonstrated that E. coli isolates exhibiting LA are isolated significantly more often from infants and young children with diarrhea than from matched controls (3, 6, 7); the vast majority of such isolates fall into classical EPEC O serogroups (3). Diffuse adherence E. coli (DAEC) are probably the least studies and understood of the HEp-2 cell adherent E. coli. In the one strain extensively studied, diffuse adherence requires the expression of antigenically distinct fimbriae, the structural the expression of antigenically distinct fimbriae, the structural genes of which are chromosomal (8). There is controversy over whether of not DAEC are diarrheagenic (1, 3, 6, 7, 9, 10).