Differences in Bacterial Translocation Across the Large andSmall Bowel Walls after Ischemia and Reperfusion Injury

ABSTRACT

PURPOSE: Bacterial translocation is a major problem after ischemic bowel injuries such as mesenteric vessel obstruction or bowel strangulation. In this study, we investigated the differential character of bacterial translocation from the large and small bowel using Escherichia coli labeled with technetium 99m (99mTc-E.coli). METHOD: Male Sprague-Dawley rats weighing 200~300 g underwent laparotomy. The superior mesenteric artery and marginal arteries of the proximal jejunum and distal colon were occluded for 30 minutes and then re-perfused for 4 hours. A suspension containing 99mTc-E.coli was injected into the lumen of the proximal colon (group 1) and distal ileum (group 2). In the sham operation group (groups 3, 4), 99mTc-E.coli was also injected in the same manner without induction of ischemia and reperfusion injury. Two hours after E. coli injection, blood, mesenteric lymph nodes (MLN), liver, spleen, and lung were collected for quantitative analysis of radioactivity. Large and small bowel specimens were also harvested for microscopic examination. Student's t-test was used for statistical analysis. P< or =0.05 was considered statistically significant. RESULT: Compared with group 1, group 2 showed a significant increase in 99mTc-E.coli translocation from the lumen to all organs investigated, except with regard to MLN. The sham operation group (groups 3, 4) showed scanty bacterial translocation. The mucosal epithelial cell layers of both groups (groups 1, 2) were comparatively intact. CONCLUSION: The 99mTc-E.coli method was found to be suitable for studies of bacterial translocation from the small and large bowels. Bacterial translocation is much more likely to occur across the small bowel wall than across the large bowel wall.