The relationship between small-intestinal bacterial overgrowth and intestinal permeability in patients with irritable bowel syndrome

Background/Aims: Small-intestinal bacterial overgrowth (SIBO) is a frequent finding in patients with irritable bowel syndrome (IBS). Many patients with IBS also have abnormal intestinal permeability, which is probably due to low-grade inflammation in the intestinal mucosa. Our aim was to verify the relationship between SIBO and small-intestinal permeability in IBS patients. Methods: A cohort of 38 IBS patients (20 women and 18 men; age range 16-70 years; mean age 40.2 years) with symptoms that fulfilled Rome-II criteria, and 12 healthy controls (5 women and 7 men; age range 25-52 years; mean age: 37.8 years) were recruited. All subjects underwent lactulose breath tests (LBTs) and intestinal permeability tests using the polyethylene glycol (PEG) 3350/400 retrieval ratio. Results: A positive LBT was found in 18.4% (7/38) of patients with IBS and 8.3% (1/12) of control subjects. Intestinal permeability was significantly increased in patients with IBS compared with the normal controls (0.82±0.09 vs 0.41±0.05 [mean±SD], respectively; p<0.05). However, the intestinal permeability did not differ significantly between IBS patients with a positive LBT and those with a negative LBT (0.90±0.13 and 0.80±0.11, respectively; p>0.05). Conclusions: Intestinal permeability was increased in patients with IBS, but this finding did not correlated with the occurrence of SIBO.