Although controversial, small intestinal bacterial overgrowth (SIBO) has been associated with irritable bowel syndrome (IBS) (1). However, little is known regarding the effect of concomitant SIBO in patients with IBS in terms of symptom burden, quality of life or its effect on gastrointestinal (GI) motility. We aimed to compare the effect of SIBO on symptom burden, quality of life and segmental/panenteric motility in IBS.Methods
27 patients with Rome III defined IBS-mixed bowel habit (IBS-M) (3 male, mean age 36.5 years, range 18–65) underwent a wireless motility capsule (WMC) using a standardised protocol. The WMC concurrently measures pH, pressure and temperature as it traverses the GI tract. Segmental transit was derived from measures around known anatomical landmarks as identified by compartmental pH changes. Ileal and colonic motility measures are presented as area under the curve (AUC) derived from contraction amplitude and frequency. Validated questionnaires assessing GI (verbal descriptor anchored visual analogue scale (VDVAS) assessing sensory intensity (VDVAS-I) and unpleasantness (VDVAS-U)), somatic symptoms (Personal Health Questionnaire (PHQ) and quality of life (EQ-5 D) were administered. A standardised lactulose hydrogen breath test was subsequently performed and interpreted according to recently published guidelines (2).Results
14/27 patients (51.8%) were positive for SIBO based on breath testing. Changes in GI motility between SIBO positive and negative patients are shown in Table 1. Patients with concomitant SIBO had higher VDVAS-I and VDVAS-U (147±21 vs. 127±20, p≥0.048 and 135±9.2 vs. 109±6.2, p≥0.02) and somatic symptoms (9.8±3.2 vs. 7.3±2.3, p≥0.03). SIBO positive patients had reduced quality of life in comparison to those without (43.2±16 vs. 60±15, p≥0.008).Conclusions
Concomitant SIBO in patients with IBS-M confers a higher gastrointestinal and extra-gastrointestinal symptom burden. Moreover, it is associated with a reduction in quality of life. However, it was not associated with any demonstrable alterations in GI physiology. It is plausible to suggest that such IBS patients with co-existent SIBO may potentially preferentially respond to antimicrobial interventions such as rifaximin.