THE ROLE OF SMALL INTESTINAL BACTERIAL OVERGROWTH IN THE PATHOGENESIS, MANAGEMENT AND QUALITY OF LIFE IN PATIENTS WITH IRRITABLE BOWEL SYNDROME – A LITERATURE REVIEW
DOI:
https://doi.org/10.31435/ijitss.2(50).2026.5210Keywords:
SIBO, Irritable Bowel Syndrome, Treatment, Quality of Life, Bioengineering, Artificial IntelligenceAbstract
Background: Small intestinal bacterial overgrowth (SIBO) contributes significantly to the pathogenesis and symptom severity of irritable bowel syndrome (IBS). It is associated with microbial dysbiosis, abnormal intestinal gas fermentation, altered motility, and systemic metabolic and neurocognitive effects, including brain fogginess. Diagnostic uncertainty and lack of a universally accepted gold standard complicate clinical management.
Aim: This review synthesizes current evidence on disease mechanisms, diagnostic challenges, therapeutic strategies, and the impact on patient quality of life in SIBO-associated IBS.
Methods: A literature search was conducted in PubMed, Scopus, and Google Scholar for full-text articles published between 2000 and 2025. Clinical studies, systematic reviews, and meta-analyses addressing pathophysiology, diagnostics, and treatment outcomes were included.
Results: Microbial dysbiosis exacerbates gastrointestinal symptoms through excessive gas production and disrupted motility. Patients frequently report cognitive impairments, including brain fogginess, alongside gastrointestinal distress. Targeted therapy with nonabsorbable antibiotics provides significant symptom relief and improves functional capacity. Persistent diagnostic challenges underscore the need for standardized breath testing and microbial assessments to guide management.
Conclusion: Incorporating specific microbial diagnostics into routine gastroenterological practice is essential for optimizing treatment in SIBO-associated IBS. Recognizing the multifaceted impact of bacterial overgrowth enables clinicians to implement targeted therapies, address both intestinal and systemic consequences, and improve long-term patient outcomes.
References
Bashashati, M., Rezaei, N., Shafieyoun, A., McKernan, D. P., Chang, L., Öhman, L., Quigley, E. M. M., Schmulson, M., Sharkey, K. A., & Simrén, M. (2014). Cytokine imbalance in irritable bowel syndrome: A systematic review and meta-analysis. Neurogastroenterology & Motility, 26(7), 1036–1048. https://doi.org/10.1111/nmo.12358
Böhm, M., Siwiec, R. M., & Wo, J. M. (2013). Diagnosis and management of small intestinal bacterial overgrowth. Nutrition in Clinical Practice, 28(3), 289–299. https://doi.org/10.1177/0884533613485882
Camilleri, M. (2012). Peripheral mechanisms in irritable bowel syndrome. New England Journal of Medicine, 367(17), 1626–1635. https://doi.org/10.1056/NEJMra1207068
Canavan, C., West, J., & Card, T. (2014). Review article: The economic impact of irritable bowel syndrome. Alimentary Pharmacology & Therapeutics, 40(9), 1023–1034. https://doi.org/10.1111/apt.12938
Chen, B., Kim, J. J., Zhang, Y., Du, L., & Chen, X. (2018). Prevalence and predictors of small intestinal bacterial overgrowth in irritable bowel syndrome: A systematic review and meta-analysis. Journal of Gastroenterology, 53(7), 807–818. https://doi.org/10.1007/s00535-018-1476-9
Chey, W. D., Kurlander, J., & Eswaran, S. (2015). Irritable bowel syndrome: A clinical review. JAMA, 313(9), 949–958. https://doi.org/10.1001/jama.2015.0954
Chuah, K. H., Hian, W. X., Lim, S. Z., Beh, K. H., & Mahadeva, S. (2023). Impact of small intestinal bacterial overgrowth on symptoms and quality of life in irritable bowel syndrome. Journal of Digestive Diseases, 24(3), 194–202. https://doi.org/10.1111/1751-2980.13189
Dray, X., Iakovidis, D., Houdeville, C., Jover, R., Diamantis, D., Histace, A., & Koulaouzidis, A. (2021). Artificial intelligence in small bowel capsule endoscopy: Current status, challenges and future promise. Journal of Gastroenterology and Hepatology, 36(1), 12–19. https://doi.org/10.1111/jgh.15341
Ford, A. C., Lacy, B. E., & Talley, N. J. (2017). Irritable bowel syndrome. New England Journal of Medicine, 376(26), 2566–2578. https://doi.org/10.1056/NEJMra1607547
Ford, A. C., Lacy, B. E., & Talley, N. J. (2017). Irritable bowel syndrome. The Lancet, 391(10122), 1675–1688. https://doi.org/10.1016/S0140-6736(20)31548-8
Ford, A. C., Spiegel, B. M. R., Talley, N. J., & Moayyedi, P. (2009). Small intestinal bacterial overgrowth in irritable bowel syndrome: Systematic review and meta-analysis. Clinical Gastroenterology and Hepatology, 7(12), 1279–1286. https://doi.org/10.1016/j.cgh.2009.06.031
Frändemark, Å., Törnblom, H., Jakobsson, S., & Simrén, M. (2018). Work productivity and activity impairment in irritable bowel syndrome (IBS): A multifaceted problem. The American Journal of Gastroenterology, 113(10), 1540–1549. https://doi.org/10.1038/s41395-018-0262-x
Ghoshal, U. C. (2011). How to interpret hydrogen breath tests. Journal of Neurogastroenterology and Motility, 17(3), 312–317. https://doi.org/10.5056/jnm.2011.17.3.312
Ghoshal, U. C., Shukla, R., & Ghoshal, U. (2017). Small intestinal bacterial overgrowth and irritable bowel syndrome: A bridge between functional organic dichotomy. Gut and Liver, 11(2), 196–208. https://doi.org/10.5009/gnl16126
Gibson, P. R., & Shepherd, S. J. (2010). Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach. Journal of Gastroenterology and Hepatology, 25(2), 252–258. https://doi.org/10.1111/j.1440-1746.2009.06149.x
Grace, E., Shaw, C., Whelan, K., & Andreyev, H. J. N. (2013). Small intestinal bacterial overgrowth: Prevalence, clinical features, current and developing diagnostic tests, and treatment. Alimentary Pharmacology & Therapeutics, 38(7), 674–688. https://doi.org/10.1111/apt.12456
Kalantar-Zadeh, K., Berean, K. J., Ha, N., Chrimes, A. F., Xu, K., Grando, D., Ou, J. Z., Pillai, N., Campbell, J. L., Brkljača, R., Taylor, K. J., Wang, R. E., Yao, C. K., Ward, S. A., McSweeney, C. S., Muir, J. G., & Gibson, P. R. (2018). A human pilot trial of ingestible electronic capsules capable of sensing different gases in the gut. Nature Electronics, 1(1), 79–87. https://doi.org/10.1038/s41928-017-0004-x
Khoshini, R., Dai, S. C., Lezcano, S., & Pimentel, M. (2008). A systematic review of diagnostic tests for small intestinal bacterial overgrowth. Digestive Diseases and Sciences, 53(6), 1443–1454. https://doi.org/10.1007/s10620-007-0065-1
Kunkel, D., Basseri, R. J., Makhani, M. D., Chong, K., Chang, C., & Pimentel, M. (2011). Methane on breath testing is associated with constipation: A systematic review and meta-analysis. Digestive Diseases and Sciences, 56(6), 1612–1618. https://doi.org/10.1007/s10620-011-1590-5
Mărginean, C. O., Meliț, L. E., & Săsăran, M. O. (2024). The relationship between small intestinal bacterial overgrowth and constipation in children: A comprehensive review. Frontiers in Cellular and Infection Microbiology, 14, Article 1431660. https://doi.org/10.3389/fcimb.2024.1431660
Mayer, E. A., Gupta, A., & Kilpatrick, L. A. (2014). Brain-gut-microbiome interactions in irritable bowel syndrome. Gastroenterology, 146(6), 1500–1512. https://doi.org/10.1053/j.gastro.2014.02.037
Mayer, E. A., Tillisch, K., & Gupta, A. (2015). Gut/brain axis and the microbiota. Journal of Clinical Investigation, 125(3), 926–938. https://doi.org/10.1172/JCI76304
Osadchiy, V., Martin, C. R., & Mayer, E. A. (2019). The gut-brain axis and the microbiome: Mechanisms and clinical implications. Clinical Gastroenterology and Hepatology, 17(2), 322–332. https://doi.org/10.1016/j.cgh.2018.10.002
Pimentel, M., Chow, E. J., & Lin, H. C. (2000). Eradication of small intestinal bacterial overgrowth reduces symptoms of irritable bowel syndrome. American Journal of Gastroenterology, 95(12), 3503–3506. https://doi.org/10.1111/j.1572-0241.2000.03368.x
Pimentel, M., Constantino, T., Kong, Y., Bajwa, M., Rezaei, A., & Park, S. (2004). A 14-day elemental diet is highly effective in normalizing the lactulose breath test. Digestive Diseases and Sciences, 49(1), 73–77. https://doi.org/10.1023/B:DDAS.0000011605.43979.el
Pimentel, M., Lembo, A., Chey, W. D., Zakko, S., Ringel, Y., Yu, J., Mareya, S. M., Shaw, A. L., Bortey, E., & Forbes, W. P. (2011). Rifaximin therapy for patients with irritable bowel syndrome without constipation. The New England Journal of Medicine, 364(1), 22–32. https://doi.org/10.1056/NEJMoa1004409
Pimentel, M., Lin, H. C., Enayati, P., van den Burg, B., Lee, H. R., Chen, J. H., Park, S., Kong, Y., Conklin, J., & Soffer, E. E. (2006). Methane, a gas produced by enteric bacteria, slows intestinal transit and augments small intestinal contractile activity. The American Journal of Physiology-Gastrointestinal and Liver Physiology, 290(6), G1089–G1095. https://doi.org/10.1152/ajpgi.00574.2004
Pimentel, M., Low, K., Hwang, L., Hua, J., Zhu, A., & Morales, W. (2010). A combination of rifaximin and neomycin is most effective in treating irritable bowel syndrome patients with methane on lactulose breath test. Journal of Clinical Gastroenterology, 44(8), 547–550. https://doi.org/10.1097/MCG.0b013e3181c64c90
Pimentel, M., Morales, W., Lezcano, S., Sun-Chuan, D., Low, K., & Yang, J. (2009). Low-dose nocturnal tegaserod or erythromycin delays symptom recurrence after treatment of irritable bowel syndrome based on presumed bacterial overgrowth. Gastroenterology & Hepatology, 5(6), 435–442. https://pubmed.ncbi.nlm.nih.gov/20574504/
Pimentel, M., Morales, W., Rezaie, A., Marsh, E., Lembo, A., Mirocha, J., Leffler, D. A., Shao, Z., Choung, R. S., Wouters, E., Talley, N. J., & Chang, C. (2015). Development and validation of a biomarker for diarrhea-predominant irritable bowel syndrome. PLOS ONE, 10(5), Article e0126438. https://doi.org/10.1371/journal.pone.0126438
Quigley, E. M. M. (2018). The gut-brain axis and the microbiome: Clues to pathophysiology and opportunities for novel management strategies in irritable bowel syndrome. Journal of Clinical Medicine, 7(1), Article 6. https://doi.org/10.3390/jcm7010006
Quigley, E. M. M. (2019). The spectrum of small intestinal bacterial overgrowth (SIBO). Current Gastroenterology Reports, 21(1), Article 3. https://doi.org/10.1007/s11894-019-0671-z
Rao, S. S. C., & Bhagatwala, J. (2019). Small intestinal bacterial overgrowth: Clinical features and therapeutic strategies. Clinical and Translational Gastroenterology, 10(10), Article e00078. https://doi.org/10.14309/ctg.0000000000000078
Rao, S. S. C., Rehman, A., Yu, S., & de Andino, N. M. (2018). Brain fogginess, gas and bloating: A link between small intestinal bacterial overgrowth, probiotics and metabolic acidosis. Clinical and Translational Gastroenterology, 9(6), Article e162. https://doi.org/10.1038/s41424-018-0030-7
Rezaie, A., Buresi, M., Lembo, A., Lin, H., McCallum, R., Rao, S., Schmulson, M., Valdovinos, M., Zakko, S., & Pimentel, M. (2017). Hydrogen and methane-based breath testing in gastrointestinal disorders: The North American Consensus. The American Journal of Gastroenterology, 112(5), 775–784. https://doi.org/10.1038/ajg.2017.46
Ringel, Y., & Maharshak, N. (2013). Intestinal microbiota and immune function in the pathogenesis of irritable bowel syndrome. American Journal of Physiology-Gastrointestinal and Liver Physiology, 305(8), G529–G541. https://doi.org/10.1152/ajpgi.00207.2012
Saleem, M. M., Masood, S., Rahmatullah, M. M., Imdad, I. A., Sange, A. M. A., & Nasr, D. (2025). Gut microbiota dysbiosis and its role in the development of irritable bowel syndrome. Cureus, 17(4), Article e83084. https://doi.org/10.7759/cureus.83084
Shah, A., Talley, N. J., Jones, M., Kendall, B. J., Koloski, N., Walker, M. M., Morrison, M., & Holtmann, G. J. (2020). Small intestinal bacterial overgrowth in irritable bowel syndrome: A systematic review and meta-analysis of case-control studies. The American Journal of Gastroenterology, 115(2), 190–201. https://doi.org/10.14309/ajg.0000000000000504
Shah, S. C., Day, L. W., Somsouk, M., & Sewell, J. L. (2013). Meta-analysis: Antibiotic therapy for small intestinal bacterial overgrowth. Alimentary Pharmacology & Therapeutics, 38(8), 925–934. https://doi.org/10.1111/apt.12479
Shrestha, B., Patel, D., Shah, H., Hanna, K. S., Kaur, H., Alazzeh, M. S., Thandavaram, A., Channar, A., Purohit, A., & Venugopal, S. (2022). The role of gut microbiota in the pathophysiology and therapy of irritable bowel syndrome: A systematic review. Cureus, 14(8), Article e28064. https://doi.org/10.7759/cureus.28064
Simrén, M., Barbara, G., Flint, H. J., Spiegel, B. M. R., Spiller, R. C., Vanner, S., Verdu, E. F., Whorwell, P. J., & Zoetendal, E. G. (2013). Intestinal microbiota in functional bowel disorders: A Rome Foundation report. Gastroenterology, 144(5), 1180–1191. https://doi.org/10.1136/gutjnl-2012-302167
So, D., Quigley, E. M. M., & Whelan, K. (2023). Probiotics in irritable bowel syndrome and inflammatory bowel disease: Review of mechanisms and effectiveness. Current Opinion in Gastroenterology, 39(2), 103–109. https://doi.org/10.1097/MOG.0000000000000902
Takakura, W., & Pimentel, M. (2020). Small intestinal bacterial overgrowth and irritable bowel syndrome: An update on pathophysiology, diagnosis, and treatment. Frontiers in Psychiatry, 11, Article 664. https://doi.org/10.3389/fpsyt.2020.00664
Xie, X., Chen, Y. Y., Zhong, T. T., et al. (2022). Development and validation of an artificial intelligence model for small bowel capsule endoscopy video review. JAMA Network Open, 5(7), Article e2221992. https://doi.org/10.1001/jamanetworkopen.2022.21992
Xu, D., Chen, V. L., Steiner, C. A., Berinstein, J. A., Eswaran, S., Waljee, A. K., Higgins, P. D. R., & Owyang, C. (2019). Efficacy of fecal microbiota transplantation in irritable bowel syndrome: A systematic review and meta-analysis. The American Journal of Gastroenterology, 114(7), 1043–1050. https://doi.org/10.14309/ajg.0000000000000198
Zhong, C., Qu, C., Wang, B., Liang, S., & Zeng, B. (2017). Probiotics for preventing and treating small intestinal bacterial overgrowth: A meta-analysis and systematic review of current evidence. Journal of Clinical Gastroenterology, 51(4), 300–311. https://doi.org/10.1097/MCG.0000000000000814
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Copyright (c) 2026 Karolina Dąbrowska, Emilia Lenkiewicz, Alicja Maciejewska, Monika Stepinska, Marta Omiecińska, Maja Kaczor, Weronika Trynkiewicz , Zuzanna Rybka , Julia Żak , Jakub Winiarczyk
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