Small Intestinal Bacterial Overgrowth in Patients with Irritable Bowel Syndrome: Clinical Characteristics, Psychological Factors, and Peripheral Cytokines.

Hua Chu,Ning Dai,Lijun Du,Yanyong Deng,Xia Zheng,Yanqin Long,Zhihui Huang,Mark Fox,Fei Xu

doi:10.1155/2016/3230859

Abstract

Small intestinal bacterial overgrowth (SIBO) has been implicated in the pathogenesis of irritable bowel syndrome (IBS). Psychosocial factors and low-grade colonic mucosal immune activation have been suggested to play important roles in the pathophysiology of IBS. In total, 94 patients with IBS and 13 healthy volunteers underwent a 10 g lactulose hydrogen breath test (HBT) with concurrent 99mTc scintigraphy. All participants also completed a face-to-face questionnaire survey, including the Hospital Anxiety and Depression Scale, Life Event Stress (LES), and general information. Serum tumour necrosis factor-α, interleukin- (IL-) 6, IL-8, and IL-10 levels were measured. The 89 enrolled patients with IBS and 13 healthy controls had no differences in baseline characteristics. The prevalence of SIBO in patients with IBS was higher than that in healthy controls (39% versus 8%, resp.; p = 0.026). Patients with IBS had higher anxiety, depression, and LES scores, but anxiety, depression, and LES scores were similar between the SIBO-positive and SIBO-negative groups. Psychological disorders were not associated with SIBO in patients with IBS. The serum IL-10 level was significantly lower in SIBO-positive than SIBO-negative patients with IBS.

Highlights

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder (FGID) characterised by recurrent abdominal pain or discomfort associated with alterations in stool frequency and/or consistency, for which there is no apparent physical or biochemical cause to explain the symptoms
Small intestinal bacterial overgrowth (SIBO) has been suggested to play a role in the pathophysiology of irritable bowel syndrome (IBS), but the reported prevalence of SIBO in patients with IBS varies widely depending on the geographical origin of the study population, methods for detection, and criteria for diagnosing SIBO
Our results demonstrate that the prevalence of SIBO was higher in patients with IBS than in healthy controls, as we showed previously [10]

Summary

Introduction

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder (FGID) characterised by recurrent abdominal pain or discomfort associated with alterations in stool frequency and/or consistency, for which there is no apparent physical or biochemical cause to explain the symptoms. Visceral hypersensitivity and abnormal gastrointestinal motility are possible major pathophysiologies, but other factors may include brain-gut dysfunction, psychological disorders, dietary issues, gastrointestinal infections, and genetics. Low intestinal motility and immune activation may explain SIBO in a patient with IBS. Bacterial products, such as endotoxins, can affect gut motility [12]. Immune-mediated cytokines have multiple actions, including altered epithelial secretion, exaggerated nociceptive signalling, and abnormal motility [13]. Together, these changes may lead to IBS. This study was designed to examine the clinical characteristics, psychological states, and serum cytokine levels in patients with IBS and SIBO to better understand the pathology of IBS

Materials and Methods

Results

Discussion