THE ROLE OF INTERDIGESTIVE SMALL-BOWEL MOTILITY IN THE REGULATION OF GUT MICROFLORA, BACTERIAL OVERGROWTH, AND BACTERIAL TRANSLOCATION IN RATS

Objective To clarify the role of the migrating motor complex (MMC) in the regulation of small intestinal microflora and bacterial translocat ion. Summary Background Data The intestinal microflora may serve as a source of infectious microorganisms. Failure of regulatory mechanisms of the intestinal flora could therefore play an important role in the pathogenesis of gut-derived infections. Methods Rats were fitted with small intestinal myoelectrodes. MMCs were measured on a control day an d 3 consecutive days during continuous administration of morphine or p lacebo. Mesenteric lymph nodes, liver, spleen, peripheral blood, duode num, and ileum samples were cultured quantitatively. Results The mean MMC cycle length in placebo-treated animals was 15.1 +/- 0.5 minutes. MMCs were completely disrupted after morphine treatment. Total bacteri al growth in the duodenum was 7.27 +/- 0.34 (10)log colony-forming uni ts (CFU)/g with placebo and 8.28 +/- 0.27 CFU/g with morphine. In plac ebo-treated animals, the mean MMC cycle length the day before culturin g correlated with total bacterial growth in the duodenum. Translocatio n incidences to the mesenteric lymph nodes, liver, spleen, and blood w ere 0/8, 1/8, 0/8, and 0/8 with placebo and 7/8, 6/8, 5/8, and 0/8 wit h morphine. The overall translocation incidence was 1/8 in placebo-tre ated animals and 8/8 in morphine-treated animals. Conclusions The MMC is an important mechanism controlling bacterial growth in the upper sm all bowel. Its disruption with morphine promotes duodenal bacterial ov ergrowth and bacterial translocation.