S1274 Bacterial Overgrowth and Mucosal Inflammation in Irritable Bowel Syndrome

Abstract

Introduction: A high prevalence of small bowel bacterial overgrowth (SBBO) has been reported in Irritable Bowel Syndrome (IBS) patients potentially contributing to symptoms. Low grade mucosal inflammation has also been implicated in at least a subset of patients. However, no relationship has been demonstrated between inflammation and the presence of bacterial overgrowth in IBS patients. The aim of this study was to investigate the prevalence of SBBO in IBS patients using the combined 14C-xylose/lactulose breath test and to correlate the presence of SBBO with mucosal inflammation assessed by faecal calprotectin levels. Methods: Forty-nine IBS patients (53.78±2.19yrs) who fulfilled the ROME II criteria and 26 healthy controls (50.62±3.24yrs) were enrolled. IBS patients were further categorised into diarrhoea predominant (n=25), constipation predominant (n=7) or mixed IBS (n=15). After an overnight fast, all subjects underwent a 14C-xylose/lactulose breath test. Breath samples were collected before ingestion of the test solution and at 30min intervals for 240min and analysed for CO2, H2 and CH4. In addition, stool samples were collected for a faecal calprotectin assay (normal 0.05). It was interesting to note that 50% of the IBS patients positive for mucosal inflammation were also positive for SBBO. Specifically these patients were exclusively positive for the 14C xylose breath test (p<0.05). Conclusion: In this study, SBBO was not more prevalent in IBS patients compared with healthy age matched controls. Inflammation was present in 50% of patients with IBS who had SBBO and in no healthy controls. The positive 14C xylose breath test in this group of IBS patients suggests that specific colonising organisms may be responsible for the inflammatory response and further studies are required.