USE OF CULTURED HUMAN INTESTINAL MUCOSA TO SELECT FOR ENTEROTOXIGENIC ESCHERICHIA COLI |[lpar]|ETEC|[rpar]| PRODUCING COLONIZATION FACTORS |[lpar]|CF'S|[rpar]|: IDENTIFICATION OF A NEW FIMBRIAL CF IN ETEC SEROGROUP 0148

摘要

Three important fimbrial CF's designated CFA/I, CFA/II and E8775 were originally identified in some human ETEC strains because of their haemagglutination (HA) properties. In an attempt to identify new CF's in the many ETEC isolates which lack HA properties we have exploited the ability of human ETEC to adhere to human small intestinal mucosa. ETEC strain B7A(0148:H28) was selected for study because it belongs to a commonly isolated sero-type, does not produce CFA/I, CFA/II or E8775 and yet is known to be pathogenic when fed to volunteers. 25ul of a broth culture of B7A was placed onto the mucosal surface of duodenal biopsies maintained in organ culture. The number of mucosally adherent bacteria, assessed by scanning electron microscopy, was observed to increase with time following inoculation and after 10-12 hours virtually the whole of the mucosa was colonized by bacteria. Mucosally adherent bacteria were then subcultured and examined by negative stain electron microscopy. A new fimbrial CF morphologically and antigenically distinct from CFA/I, CFA/II and E8775 fimbriae and consisting of 3-4 nm diameter fibrils was readily identified. This selection and enrichment procedure may provide a general method for the identification of adhesion fimbriae in the many ETEC isolates which lack known CF's.