Jejunoileal bypass: change in the flora of the small intestine and its clinical impact.

Among the complications of jejunoileal bypass for morbid obesity are proctitis, bypass enteritis, liver disease, dermatitis, and arthritis, all of which are thought to be connected with the intestinal microflora. Quantitative cultures from the small bowel of patients before the establishment of the bypass and from patients with reoperations indicate colonization of both the functioning small bowel (bacterial counts, 10(5.0)-10(7.6)/ml) and of the bypassed loop (bacterial counts, 10(6.4)-10(9.7)/ml). Experiments in animals have shown that the presence of a bypassed loop, as compared with that of a resected bowel, is necessary for increased weight loss and for the development of liver disease. Clinical evidence for the impact of the intestinal microflora is based on the beneficial effect of antimicrobial agents, especially metronidazole, and on the demonstration of immunologic phenomena involving antigens of bacterial origin. Complications of jejunoileal bypass may serve to elucidate the pathogenesis of other diseases.