Aspects Of Colonisation Of The Mouse Intestine By Coliform Bacteria

The suckling NCS mouse proved to be a more sensitive and a more consistent subject for intestinal colonisation than the conventional suckling mouse.

An oral challenge dose with (5–10) x 106 coliforms, enteropathogenic or non-pathogenic, was followed by intestinal colonisation. The clearance of the introduced strains from the gut started at the weaning period in mice and was usually complete at 25–30 days of age.

However, the NCS mouse proved to be a suitable model for the differentiation of enteropathogenic from non-pathogenic coliforms on the basis of mortality, as only the enteropathogenic virulent E. coli serotypes caused deaths, apparently due to toxic effects.

Sections from the intestine of mice infected orally with doses of 106 E. coli 026:B6 or 0111:B4 showed no pathological changes.

Lung infections, following the oral challenge of mice with coliform strains, did not seem to be the sole cause of deaths as infections of the lungs via the intranasal route were not associated with mortality.

The dynamics of the implantation and of the clearance of intestinal coliforms were considered. Antagonistic activities involving the introduced coliforms and the resident bacterial groups such as coliforms, enterococci, lactobacilli and bacteroides were not observed.