The relationship between small intestinal bacterial overgrowth and irritable bowel syndrome.

OBJECTIVE: To explore the relationship between small intestinal bacterial overgrowth (SIBO) and irritable bowel syndrome (IBS). PATIENTS AND METHODS: Fifty IBS patients in the hospital from January 2015 to December 2015 were assigned to the treatment group, and 50 healthy persons were assigned to the control group. Lactulose hydrogen and methane breath test were performed to measure the percentage of SIBO and oro-cecal transit time (OCTT) in treatment group and control group. These subjects were further assigned to negative SIBO group and positive SIBO group to analyze the scores of symptoms. RESULTS: The percentage of positive SIBO in the treatment group (72%, 36/50) was significantly higher (p<0.05) than the control group (38%, 19/50). The scores of symptoms on the episode of IBS were not significantly different between the positive SIBO subgroup and the negative SIBO subgroup. The scores of symptoms in breath test were not significantly different between the positive SIBO subgroup and the negative SIBO subgroup. The OCTT in the treatment group (69.34±1.27 min) was significantly lower (p<0.05) than the control group (85.16±1.75 min). The OCTT in the positive SIBO group (88.57±4.62 min) was significantly higher (p<0.05) than the control group (73.42±5.25 min). The results of lactulose hydrogen and methane breath test in the treatment group were positively correlated (r = 0.987, p<0.01). The results of lactulose hydrogen and methane breath test in the control group after oral administration of lactulose were also positively correlated (r = 0.736, p<0.01). CONCLUSIONS: SIBO was related to IBS and could prolong OCTT, yet not worsen IBS.