Frequency of Small Intestinal Bacterial Overgrowth in Patients with Irritable Bowel Syndrome and Chronic Non-Specific Diarrhea

INTRODUCTION: Small intestinal bacterial overgrowth (SIBO) occurs in varying frequency in irritable bowel syndrome (IBS). We studied the frequency of SIBO in IBS and chronic non-specific diarrhea (CNSD). METHODS: 129 patients with IBS (Manning's criteria), 73 with CNSD (≥ 4 weeks diarrhea with two of these tests normal [urine D-xylose, fecal fat and duodenal biopsy]) and 51 healthy controls (HC) were evaluated for SIBO using glucose hydrogen breath test (GHBT). Diarrhea-predominant IBS (D-IBS) was grouped into CNSD. Rise in breath hydrogen 12 ppm above basal following 100 g glucose was diagnostic of SIBO. RESULTS: Of 129 patients with IBS, 7 were constipation (C-IBS), and 122 were of indeterminate type (I-IBS). Patients with IBS were younger than HC and CNSD (IBS vs. HC: 36.6 yr ± 11.4 vs. 44.1 yr ± 13.6, p = 0.001; IBS vs. CNSD: 36.6 yr ± 11.4 vs. 42 yr ± 14.5, p = 0.003). Patients with CNSD were comparable to HC in age (42 yr ± 14.5 vs. 44.1 yr ± 13.6, p = ns). Patients with IBS were more often male than HC [108/129 (83.7%) vs. 34/51 (66.7%) p = 0.02]; gender of CNSD and HC was comparable [male 39/73 (53.4%) vs. 34/51 (66.7%) p = ns]. SIBO was commoner in CNSD than HC [16 (21.9%) vs. 1 (2%), p = 0.003], but was comparable in IBS and HC [11 (8.5%) vs. 1 (2%), p = 0.18]. Patients with CNSD more often had SIBO than IBS [16 (21.9%) vs. 11 (8.5%), p = 0.007]. CONCLUSIONS: SIBO was more common in CNSD including D-IBS than other types of IBS and HC.