ABNORMAL INTESTINAL MOTOR PATTERNS EXPLAIN ENTERIC COLONIZATION WITH GRAM-NEGATIVE BACILLI IN LATE RADIATION ENTEROPATHY

Background & Aims: Bacterial overgrowth and intestinal pseudo-obstruct ion may succeed abdominal radiotherapy, and absence of intestinal migr ating motor complex (MMC) has been reported in bacterial overgrowth. T he aims of this study were to address the relationship between intesti nal patterns of motility and gastrointestinal microflora and to elucid ate the pathogenesis of late radiation enteropathy. Methods: Forty-one consecutive female patients with symptoms of late radiation enteropat hy were examined by prolonged ambulatory manometry, culture of gastric and duodenal samples with quantification of gram-negative bacilli (GN B) by the glucose gas test, the [C-14]D-xylose breath test, and determ ination of pH and short-chain fatty acids in gastric juice. Results: T he intensity of MMC explained 61% (P < 0.001) and 71% (P < 0.001) of t he variability of GNB in the stomach and duodenum, respectively, corre sponding to the severity of disease. Abnormal MMC index and presence o f irregular bursts were the best predictors of GNB (86%; P < 0.001, mu ltiple regression). Fasting gastric pH explained gastric bacterial cou nts (63%; P < 0.001) but did not predict GNB. Conclusions: Impaired mo tility emerges as a causal factor for gastrointestinal colonization wi th GNB, whereas hypochlorhydria facilitates unspecific gastric coloniz ation. Abnormal motility and GNB in the proximal small intestine are e ssential factors in the pathogenesis of severe late radiation enteropa thy.