Small intestinal bacterial overgrowth in patients with inflammatory bowel disease: A case-control study

Indian J Gastroenterol. 2022 Feb;41(1):96-103. doi: 10.1007/s12664-021-01211-6. Epub 2021 Aug 14.


Background: Though small intestinal bacterial overgrowth (SIBO) is known in inflammatory bowel disease (IBD), the data on it are scanty and have limitations.

Methods: Data on IBD patients undergoing glucose hydrogen breath test (GHBT) were retrospectively analyzed to evaluate the frequency and risk factors of SIBO in IBD compared to 66 healthy controls.

Results: Patients with IBD (n=86; 45 ulcerative colitis [UC] and 41 Crohn's disease [CD]) more often had SIBO on GHBT than the healthy subjects (16/86 [18.6%] vs. 1/66 [1.5%]; p=0.002). SIBO was commoner among patients with CD than UC (14/41 [34.1%] vs. 2/45 [4.4%]; p=0.001). The frequency of SIBO among UC patients was comparable to healthy subjects (2/45 [4.4%] vs. 1/66 [1.5%]; p=not significant [NS]). Patients with CD than those with UC had higher values of maximum breath hydrogen and a greater area under the curve for breath hydrogen. Other factors associated with SIBO included female gender (11/16 [68.8%] with vs. 21/70 [30%] without SIBO; p=0.003), and having undergone surgery (8/16 [50%] vs. 6/70 [8.6%]; p=0.0002). SIBO patients had lower levels of total serum protein and albumin than those without SIBO (6.2 ± 1.5 g/dL vs. 7.0 ± 0.9 g/dL, respectively; p=0.009 and 3.5 ± 0.9 g/dL vs. 4.0 ± 0.6 g/dL, respectively; p=0.02). CD, female gender, and surgery for IBD tended to be the independent factors associated with SIBO among IBD patients on multivariate analysis.

Conclusions: Patients with IBD, particularly CD, female, and those having undergone surgery, have a higher risk of SIBO than the healthy controls.

Keywords: Crohn’s disease; Dysbiosis; Gut aspirate culture; Gut microbiota; Harvey-Bradshaw score; Hydrogen breath test; Rifaximin; Ulcerative colitis.

MeSH terms

  • Breath Tests
  • Case-Control Studies
  • Colitis, Ulcerative* / complications
  • Crohn Disease* / complications
  • Female
  • Glucose / metabolism
  • Humans
  • Hydrogen
  • Inflammatory Bowel Diseases* / complications
  • Intestine, Small / microbiology
  • Retrospective Studies


  • Hydrogen
  • Glucose