Background & aims: Bacterial overgrowth and intestinal pseudo-obstruction may succeed abdominal radiotherapy, and absence of intestinal migrating motor complex (MMC) has been reported in bacterial overgrowth. The aims of this study were to address the relationship between intestinal patterns of motility and gastrointestinal microflora and to elucidate the pathogenesis of late radiation enteropathy.
Methods: Forty-one consecutive female patients with symptoms of late radiation enteropathy were examined by prolonged ambulatory manometry, culture of gastric and duodenal samples with quantification of gram-negative bacilli (GNB) by the glucose gas test, the [14C]D-xylose breath test, and determination of pH and short-chain fatty acids in gastric juice.
Results: The intensity of MMC explained 61% (P < 0.001) and 71% (P < 0.001) of the variability of GNB in the stomach and duodenum, respectively, corresponding to the severity of disease. Abnormal MMC index and presence of irregular bursts were the best predictors of GNB (86%; P < 0.001, multiple regression). Fasting gastric pH explained gastric bacterial counts (63%; P < 0.001) but did not predict GNB.
Conclusions: Impaired motility emerges as a causal factor for gastrointestinal colonization with GNB, whereas hypochlorhydria facilitates unspecific gastric colonization. Abnormal motility and GNB in the proximal small intestine are essential factors in the pathogenesis of severe late radiation enteropathy.