Small intestinal bacterial overgrowth and lactose intolerance contribute to irritable bowel syndrome symptomatology in Pakistan

ABSTRACT

The symptoms of irritable bowel syndrome resemble those of small intestinal bacterial overgrowth [SIBO]. The aim of this study was to determine the frequency of SIBO and lactose intolerance [LI] occurrence in patients with diarrhea-predominant irritable bowel syndrome [IBS-D] according to Rome III criteria. In this retrospective case-control study, patients over 18 years of age with altered bowel habit, bloating, and patients who had lactose Hydrogen breath test [H2 BT] done were included. The "cases" were defined as patients who fulfill Rome III criteria for IBS-D, while "controls" were those having chronic nonspecific diarrhea [CNSD] who did not fulfill Rome III criteria for IBS-D. Demographic data, predominant bowel habit pattern, concurrent use of medications, etc., were noted. Patients with IBS-D were 119 [51%] with a mean age of 35 +/- 13 years, while those with CNSD were 115 [49%] with mean age 36 +/- 15 years. Patients in both IBS-D and CNSD were comparable in gender, with male 87 [74%] and female 77 [64%]. SIBO was documented by lactose H2 BT in 32/234 [14%] cases. It was positive in 22/119 [19%] cases with IBS-D, while 10/115 [9%] cases had CNSD [P = 0.03]. LI was positive in 43/234 [18%] cases. Of these, 25/119 [21%] cases had IBS-D and 18/115 [16%] cases had CNSD [P = 0.29]. SIBO was seen in a significant number of our patients with IBS-D. There was no significant age or gender difference in patients with or without SIBO