Escherichia coli Infection

Enteroinvasive E. coli strains 1056, 1126, and 4165 have been isolated from naturally occurring cases of hamster enteritis. When inoculated into ligated intestinal loops to test for enteropathogenicity, the pathogenic strains produced changes in most of the inoculated weanling hamsters and in some of the adult animals.

Pathology

The small intestine may contain yellow to dark red fluid material. On microscopic examination, blunting and fusion of villi are frequently observed. Degeneration and sloughing of enterocytes with polymorphonuclear leukocyte infiltration in the lamina propria commonly occurs. Changes in mesenteric lymph nodes may vary from lymphoid hyperplasia to diffuse polymorpho­nuclear leukocyte infiltration. Focal coagulation necrosis in the liver, with polymorphonuclear leukocyte infiltra­tion, and gastric ulcers are other variable findings. Colitis and/or typhlitis may be present in some affected ani­mals, sometimes with concomitant colonic intussuscep­tion. Ultrastructural studies of sections of ileum have revealed bacilli in the cytoplasm of enterocytes and blunting and irregularities in microvilli. Differential diagnoses include clostridial enterotoxemia, Lawsonia- associated proliferative ileitis, and salmonellosis.