Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2017 Mar 15;11(2):196-208.
doi: 10.5009/gnl16126.

Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome: A Bridge Between Functional Organic Dichotomy

Affiliations
Free PMC article
Review

Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome: A Bridge Between Functional Organic Dichotomy

Uday C Ghoshal et al. Gut Liver. .
Free PMC article

Abstract

The pathogenesis of irritable bowel syndrome (IBS), once thought to be largely psychogenic in origin, is now understood to be multifactorial. One of the reasons for this paradigm shift is the realization that gut dysbiosis, including small intestinal bacterial overgrowth (SIBO), causes IBS symptoms. Between 4% and 78% of patients with IBS and 1% and 40% of controls have SIBO; such wide variations in prevalence might result from population differences, IBS diagnostic criteria, and, most importantly, methods to diagnose SIBO. Although quantitative jejunal aspirate culture is considered the gold standard for the diagnosis of SIBO, noninvasive hydrogen breath tests have been popular. Although the glucose hydrogen breath test is highly specific, its sensitivity is low; in contrast, the early-peak criteria in the lactulose hydrogen breath test are highly nonspecific. Female gender, older age, diarrhea-predominant IBS, bloating and flatulence, proton pump inhibitor and narcotic intake, and low hemoglobin are associated with SIBO among IBS patients. Several therapeutic trials targeting gut microbes using antibiotics and probiotics have further demonstrated that not all symptoms in patients with IBS originate in the brain but rather in the gut, providing support for the micro-organic basis of IBS. A recent proof-of-concept study showing the high frequency of symptom improvement in patients with IBS with SIBO further supports this hypothesis.

Keywords: Bacterial overgrowth; Breath tests; Dysbiosis; Gastrointestinal microbiota; Probiotics; Rifaximin.

Conflict of interest statement

CONFLICTS OF INTEREST

No potential conflict of interest relevant to this article was reported.

Figures

Fig. 1
Fig. 1
Schematic diagram showing the frequency of small intestinal bacterial overgrowth (SIBO) using quantitative jejunal aspirate culture, glucose and lactulose hydrogen breath tests (GHBT and LHBT, respectively) among patients with irritable bowel syndrome (IBS), gut defense mechanisms that prevent the development of SIBO, factors associated with SIBO among patients with IBS, and mechanisms of IBS symptom development. As shown in the figure, the frequency of SIBO in IBS patients using LHBT (early-peak criteria) is higher than that by using upper gut aspirate culture and GHBT (LHBT [45%]; upper gut aspirate culture [23%] and GHBT [26%]). Moreover, SIBO is more frequent in healthy controls using LHBT due to false positive test results (LHBT [21%], upper gut aspirate culture [1%] and GHBT [5%]). GI, gastrointestinal; IBS-D, irritable bowel syndrome, diarrhea-predominan; PPI, proton pump inhibitor; CHO, carbohydrate.

Similar articles

See all similar articles

Cited by 18 articles

See all "Cited by" articles

References

    1. Wall GC, Bryant GA, Bottenberg MM, Maki ED, Miesner AR. Irritable bowel syndrome: a concise review of current treatment concepts. World J Gastroenterol. 2014;20:8796–8806. - PMC - PubMed
    1. Ghoshal UC, Shukla R, Ghoshal U, Gwee KA, Ng SC, Quigley EM. The gut microbiota and irritable bowel syndrome: friend or foe? Int J Inflam. 2012;2012:151085. doi: 10.1155/2012/151085. - DOI - PMC - PubMed
    1. Malinen E, Krogius-Kurikka L, Lyra A, et al. Association of symptoms with gastrointestinal microbiota in irritable bowel syndrome. World J Gastroenterol. 2010;16:4532–4540. doi: 10.3748/wjg.v16.i36.4532. - DOI - PMC - PubMed
    1. Reddymasu SC, Sostarich S, McCallum RW. Small intestinal bacterial overgrowth in irritable bowel syndrome: are there any predictors? BMC Gastroenterol. 2010;10:23. doi: 10.1186/1471-230X-10-23. - DOI - PMC - PubMed
    1. Lin HC. Small intestinal bacterial overgrowth: a framework for understanding irritable bowel syndrome. JAMA. 2004;292:852–858. doi: 10.1001/jama.292.7.852. - DOI - PubMed

Substances

LinkOut - more resources

Feedback