A Study On The Relationship Between Irritable Bowel Syndrosme And Small Intestinal Bacterial Overgrowth

Background and Aims:Irritable bowel syndrome (IBS) is a common functional bowel disorder characterized by abdominal pain and abdominal discomfort associated with changes of bowel habits, which can not be explained by structural or biochemical abnormalities. Although the etiology and pathogenesis of IBS still remains unclear, probiotics and bowel motility regulators can improve symptoms in clinical practice. Due to symptoms of IBS similar to small intestinal bacterial overgrowth (SIBO), more and more studies occur to investigate the relationship between them. It is still under debate whether SIBO contributes to the pathogenesis of IBS, but most of recent studies suggest that the prevalence of SIBO increases in patients with IBS and eradication of SIBO using antibiotics can improve symptoms of IBS patients. However, few studies were conducted to investigate whether symptom improvement of IBS patients after therapy with probiotics and bowel motility regulators is associated with eradication of SIBO. This study was performed (a) to assess the prevalence of SIBO in IBS patients. (b) to investigate changes in results of lactulose hydrogen breath test (LHBT, used for diagnosing SIBO) and severity of IBS symptoms in IBS patients with SIBO after using probiotics or bowel motility regulators.Objective and Methods:151 subjects meeting the Rome III criteria of IBS were included to assess symptom severity by a questionnaire and to undergo an LHBT for diagnosing SIBO. After a positive test they were treated randomly with pinaverium bromide(bowel motility regulator, Group A) and a probiotic containing live combined Bifidobacterium, Lactobacillus and Enterococcus (Group B) for four weeks. Then subjects were secondly assessed by a follow-up questionnaire and LHBT. Statistic analysis was performed to evaluate the prevalence of SIBO in IBS patients and the eradication rate of SIBO of two treatment groups, to compare changes of LHBT and improvements of IBS symptoms between the two groups, and to compare symptom improvements between groups of eradication or non-eradication of SIBO.Results:A positive LHBT was found in 77 of 151 subjects, the prevalence of SIBO in patients with IBS was 51.0%. Patients positive for SIBO reported a significant severe abdominal bloating compared with patients without SIBO(P<0.05)and no significant differences were observed in severity of other symptoms. After four weeks' treatment, of all 56 SIBO-positive cases with a follow-up,13 of 27(48.1%) subjects in Group A had a successful eradication of SIBO, and no difference was significantly observed compared with 16 of 29(55.2%) in Group B. Both subjects in Group A and Group B reported statistically significant improvements of the IBS symptoms, whereas no significant difference was found between the two treatment groups. The scores for assessing symptom severity significantly declined after treatment for both groups of eradication or non-eradication of SIBO. Subjects with eradication of SIBO had significantly better efficacy compared to those with positive SIBO remaining after treatment(P<0.05). In IBS patients with SIBO, statistically significant association was observed in eradication of SIBO and symptom improvement (X 2=8.372, P=0.004).Conclusions:These data indicates a SIBO syndrome is present in about half of patients with an IBS diagnosis. Probiotics and bowel motility regulators can well improve symptoms of IBS. At the same time, they may bring a negative HLBT for IBS patients with SIBO. And eradication of SIBO is associated with the therapeutic effect. If SIBO is eradicated after drug treatment, IBS patients with SIBO may have a better efficacy.