Prevention of adhesion by indigenous bacteria to rabbit cecum epithelium by a barrier of microvesicles.

None of 74 strains of anaerobic bacteria cultured from the mucosal epithelial interface of the rabbit cecum adhered to isolated brush borders in experiments in which enteropathogenic Escherichia coli RDEC-1 was used as an adherent control. Scanning electron microscopy of the surfaces of the cecal epithelia confirmed that few organisms were in contact with the villus surface, but transmission electron microscopy revealed a layer of microvesicles up to 50 nm in diameter between the microvilli and mucous gel. The evidence indicates that there is no significant epithelium-adherent flora in the cecum but that a microvesicular layer could contribute significantly to prevention of adherence by both normal and potentially pathogenic bacteria.