Pathways of penetration ofEscherichia coli 055 through the intestinal wall in germfree and ordinary animals

Abstract

Permeability of the intestinal barrier in germfree animals for bacteria of the enteropathogenic strainEscherichiacoli 055 was studied. Germfree and ordinary rats and guinea pigs were used. During the first 24 h after peroral infection withE.coli 055 an increase in the bacteriemia was observed in the germfree animals, whereas in the ordinary animals the bacteriemia was transient in character. Electron-microscopic investigation of the intestinal mucosa of the germfree animals revealed disturbances of intercellular contacts and the formation of spaces containing numerous microorganisms between the enterocytes. In the germfree animals more marked changes also were found in the microvessels of the mucosa. In ordinary animals ingestion and digestion of theE.coli cells by enterocytes and leukocytes was observed. Disturbances of the intestinal barrier discovered in the germfree animals explain the increased bacteriemia in these animals in the absence of a microflora. The results point to the important role of the microbial factor in the formation of the intestinal barrier.