Bacterial flora of the small bowel before and after bypass procedure for morbid obesity.

The contents of the proximal jejunum and distal ileum were cultured quantitatively in eight patients who were undergoing intestinal bypass procedure for obesity. Five jejunal specimens were sterile, and three contained low counts of a predominantly aerobic flora. Ileal contents yielded variable but usually higher counts than in the jejunum, and there were similar numbers of anaerobes and aerobes. In three patients in whom a bypass was established, contents of the functioning small bowel showed counts of 10(5.0)-10(7.6) colony-forming units/ml. These counts exceeded the counts in the normal terminal ileum, and the flora qualitatively resembled that of feces. Four specimens from excluded loops revealed colonization with fecal organisms, and the counts ranged between 10(6.4) and 10(9.7) colony-forming units/ml. In jejunoileal bypass both the functioning small bowel and the excluded loop become colonized with colonic flora, a phenomenon that may contribute to some of the side effects of this procedure.