Constipation Predominant Irritable Bowel Syndrome (IBS-C) With Positive Lactulose Breath Test (LBT) Can Be Treated With Polyethylene Glycol (PEG) in Lieu of Antibiotics

Abstract

Introduction: Small intestinal bacterial overgrowth (SIBO) has been increasingly recognized as a pathophysiological link to irritable bowel syndrome (IBS). Different groups of bacteria in the intestine produce methane (CH4), hydrogen (H2) and carbon dioxide (CO2), which are tested in lactulose breath test (LBT). An early peak at 60 minutes is diagnostic of SIBO and a later prolonged peak at 120 minutes corresponds to colon bacteria. Studies have demonstrated the effectiveness of polyethylene glycol (PEG) in treating constipation predominant IBS (IBS-C). When compared with antibiotics, PEG is economically preferable and has fewer side effects. Aim: compare the effect of PEG and antibiotics in treating LBT positive IBS-C patients. Methods: Total of 36 patients were diagnosed as IBS-C based on Rome-III criteria with a positive LBT after reviewing medical records at our gastrointestinal center from 2011 to 2013. Ten patients received PEG and 12 received antibiotics for 14 days. LBT results of those patients were obtained prior and 2 weeks after treatment. H2, CH4 and CO2 levels at baseline, 60 minutes, and 120 minutes after ingestion of lactulose were collected. The mean levels of change were calculated and the extents of changes were compared with student t test in patients treated with PEG versus antibiotics. Results: For the patients who received PEG, prior to treatment they had mean H2 increase of 17.6 ppm and mean CH4 increase of 25.4 ppm at 60min. After PEG treatment, they had mean H2 increase of 9.2 ppm and CH4 decrease of 24 ppm at 60 min. For the patient who received antibiotics, prior to treatment they had mean H2 increase of 12 ppm at and mean CH4 increase of 33 ppm at 60 min. After antibiotics treatment, they had mean H2 increase of 8.4 ppm and mean CH4 decrease of 1.03 ppm at 60 min. There is H2 decrease after treatment at 60 min in both PEG and antibiotic treatment group. The extent of changes of H2 levels in those 2 groups were compared statistically using student T test, p value was >0.05. There is also CH4 decrease after treatment at 60 minutes in both PEG and antibiotic treatment groups. The extent of changes of CH4 levels in those 2 groups were compared statistically using student T test, p value was <0.05. Conclusion: PEG provides similar effect of H2 production in small bowel as antibiotic treatment in IBS-C LBT positive patients. PEG can reduce more CH4 production in small intestine with statistical significance which could be secondary to effect on different bacteria groups. Thus PEG could be used in lieu of antibiotics to treat LBT positive IBS-C patients. Future studies with larger sample size and with investigation of symptom improvement are needed.