ADHESION OF ENTEROAGGREGATIVE ESCHERICHIA-COLI TO PEDIATRIC INTESTINAL-MUCOSA IN-VITRO

Organ cultures of small- and large-intestinal mucosa from children wer e used to examine the interactions of enteroaggregative Escherichia ca ll (EAEC) with human intestine. Mucosae from patients aged between 3 a nd 190 months mere cultured with five EAEC strains isolated from infan ts with diarrhea in the United Kingdom and with two well-described pro totype EAEC strains, 17-2 and 221. The prototype strains adhered to je junal, ileal, and colonic mucosae. The wild-type strains also adhered to this tissue but showed a variable pattern of adhesion: two adhered to all intestinal levels, one adhered to jejunum and ileum, one adhere d to ileum only, and one adhered to ileum and colon, Adherence was in an aggregative or stacked-brick pattern, resembling that seen on HEp-2 cells. Electron microscopy of infected small intestinal mucosa reveal ed bacteria in association with a thick mucus layer above an intact en terocyte brush border, which contained extruded cell fragments. This m ucus layer aas not present on controls. EAEC adherence to colonic muco sa was associated with cytotoxic effects including microvillous vesicu lation (but without evidence of an attaching/effacing lesion), enlarge d crypt openings, the presence of intercrypt crevices, and increased e pithelial cell extrusion. These results demonstrate that in vitro orga n culture of intestinal mucosa from children can be used to investigat e EAEC pathogenesis in childhood directly. EAEC strains appear able to colonize many regions of the gastrointestinal tract, without overt ch anges to small intestinal mucosa but with cytotoxic effects on colonic mucosa.