Pili, Hemagglutination, And Adherence
The ability of enterotoxigenic Escherichia coli (ETEC) to adhere to the small bowel mucosa of both humans and animals is an important factor in the pathogenesis of diarrheal disease. The adherence has been found to be mediated by specialized protein surface antigens K88, K99, 987P, colonization factor antigens (CFA)/I CFA/II. In this adherence model system, washed buccal cells are incubated with radiolabeled ETEC strains. ETEC strains isolated from humans with diarrheal disease were found to have numerous rigid, needle-like structures on their cell surface when visualized by transmission electron microscopy. The three pili antisera were used to screen for these antigens on 106 ETEC strains isolated from human diarrheal disease. The majority of the ETEC strains in the collection are labile toxin (LT) and stable toxin (ST) producers, but ST-only and LT-only producing strains are also included. The LT-only strains were from an outbreak of diarrhea aboard a cruise ship and are bona fide pathogens.