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Too much bacteria in small intestine. Understanding Small Intestinal Bacterial Overgrowth (SIBO): Causes, Symptoms, and Treatment Options

by alexxlab

What are the main causes of Small Intestinal Bacterial Overgrowth. How does SIBO affect digestive health. What are the most common symptoms of SIBO. How is SIBO diagnosed and treated. Can dietary changes help manage SIBO. What are the potential complications of untreated SIBO. How can SIBO be prevented.

What is Small Intestinal Bacterial Overgrowth (SIBO)?

Small Intestinal Bacterial Overgrowth (SIBO) is a condition characterized by an abnormal increase in the bacterial population in the small intestine. Normally, the small intestine contains relatively few bacteria compared to the large intestine. However, in SIBO, the bacterial count in the small intestine exceeds 10^5-10^6 organisms/mL, leading to various digestive symptoms and potential complications.

SIBO can occur when the natural mechanisms that control bacterial growth in the small intestine are disrupted. These mechanisms include gastric acid secretion, intestinal motility, and the ileocecal valve function. When these protective factors are compromised, bacteria from the large intestine can migrate and proliferate in the small intestine, causing SIBO.

What Are the Main Causes of SIBO?

Several factors can contribute to the development of SIBO:

  • Structural abnormalities of the small intestine (e.g., diverticula, fistulas, or surgical alterations)
  • Reduced gastric acid production (hypochlorhydria)
  • Impaired intestinal motility
  • Immune system disorders
  • Prolonged use of certain medications (e.g., proton pump inhibitors)
  • Chronic diseases affecting the digestive system (e.g., Crohn’s disease, celiac disease)

Is SIBO more common in certain populations? Studies have shown that SIBO is more prevalent in older adults, particularly those living in residential care homes. This increased prevalence may be due to age-related changes in digestive function, reduced mobility, and the use of multiple medications.

How Does SIBO Affect Digestive Health?

SIBO can have significant impacts on digestive health and overall well-being. The overgrowth of bacteria in the small intestine can lead to:

  1. Malabsorption of nutrients
  2. Inflammation of the intestinal lining
  3. Production of harmful byproducts
  4. Disruption of the normal gut microbiome

These effects can result in various digestive symptoms and potentially lead to nutritional deficiencies if left untreated. Additionally, SIBO may contribute to the development or exacerbation of other gastrointestinal disorders, such as irritable bowel syndrome (IBS).

What Are the Most Common Symptoms of SIBO?

The symptoms of SIBO can vary from person to person, but commonly include:

  • Abdominal bloating and distension
  • Excessive gas and flatulence
  • Abdominal pain or discomfort
  • Diarrhea or constipation (or alternating between the two)
  • Nausea
  • Fatigue
  • Unintentional weight loss

Are the symptoms of SIBO similar to other digestive disorders? Yes, many SIBO symptoms overlap with those of other gastrointestinal conditions, such as IBS, making diagnosis challenging. This similarity in symptoms underscores the importance of proper diagnostic testing to differentiate SIBO from other disorders.

How is SIBO Diagnosed?

Diagnosing SIBO can be challenging due to the nonspecific nature of its symptoms. However, several diagnostic methods are available:

Breath Tests

Breath tests are non-invasive and commonly used to diagnose SIBO. These tests measure the levels of hydrogen and methane in the breath after consuming a sugar solution. Elevated levels of these gases indicate bacterial overgrowth in the small intestine.

Small Intestine Aspirate and Culture

This method involves collecting a sample of fluid from the small intestine and culturing it to identify and quantify bacterial growth. While considered the gold standard for SIBO diagnosis, it is invasive and not widely available.

Symptomatic Response to Antibiotics

In some cases, a diagnosis may be made based on a patient’s response to antibiotic treatment. Improvement of symptoms following antibiotic therapy can suggest the presence of SIBO.

Is there a single, definitive test for SIBO? Currently, there is no single test that can definitively diagnose SIBO in all cases. A combination of clinical symptoms, diagnostic tests, and sometimes a therapeutic trial may be necessary to reach a diagnosis.

What Are the Treatment Options for SIBO?

The treatment of SIBO typically involves a multi-faceted approach:

Antibiotics

Antibiotics are often the first-line treatment for SIBO. Commonly prescribed antibiotics include rifaximin, metronidazole, and neomycin. These medications help reduce the bacterial overgrowth in the small intestine.

Dietary Modifications

Dietary changes can play a crucial role in managing SIBO. Some approaches include:

  • Low FODMAP diet
  • Specific Carbohydrate Diet (SCD)
  • Elemental diet

These diets aim to reduce fermentable carbohydrates that feed bacteria in the small intestine.

Prokinetics

Medications that improve intestinal motility (prokinetics) may be prescribed to help prevent bacterial overgrowth from recurring.

Addressing Underlying Causes

Treatment should also focus on addressing any underlying conditions or factors contributing to SIBO, such as managing chronic diseases or discontinuing medications that may be promoting bacterial overgrowth.

How effective are antibiotics in treating SIBO? Studies have shown that antibiotic treatment can be effective in reducing symptoms and normalizing breath test results in many patients with SIBO. However, recurrence rates can be high, emphasizing the need for a comprehensive treatment approach that addresses underlying causes.

Can Dietary Changes Help Manage SIBO?

Dietary modifications play a crucial role in managing SIBO and preventing its recurrence. Several dietary approaches have shown promise:

Low FODMAP Diet

The Low FODMAP diet involves reducing the intake of fermentable carbohydrates that can feed bacteria in the small intestine. This approach has been shown to improve symptoms in many patients with SIBO.

Specific Carbohydrate Diet (SCD)

The SCD eliminates complex carbohydrates and most sugars, allowing only specific types of carbohydrates that are more easily digested. This diet aims to starve the bacteria causing SIBO.

Elemental Diet

An elemental diet consists of pre-digested nutrients in a liquid form. This approach can be highly effective in reducing bacterial overgrowth but is typically used for short periods due to its restrictive nature.

How long should dietary changes be maintained? The duration of dietary modifications can vary depending on individual response and the severity of SIBO. Some patients may need to follow a modified diet long-term, while others may be able to gradually reintroduce foods after successful treatment.

What Are the Potential Complications of Untreated SIBO?

If left untreated, SIBO can lead to several complications:

  • Malnutrition and vitamin deficiencies (particularly B12 and fat-soluble vitamins)
  • Osteoporosis due to calcium malabsorption
  • Anemia resulting from iron or B12 deficiency
  • Increased intestinal permeability (“leaky gut”)
  • Systemic inflammation
  • Exacerbation of other gastrointestinal disorders

Can SIBO lead to more severe gastrointestinal conditions? While SIBO itself is not typically life-threatening, it can significantly impact quality of life and potentially contribute to the development or worsening of other gastrointestinal disorders. Proper diagnosis and treatment are essential to prevent long-term complications.

How Can SIBO Be Prevented?

Preventing SIBO involves addressing the factors that contribute to its development:

  1. Maintaining a healthy diet rich in fiber and low in processed foods
  2. Managing underlying health conditions that may contribute to SIBO
  3. Avoiding unnecessary use of medications that can disrupt gut bacteria (e.g., antibiotics, proton pump inhibitors)
  4. Promoting healthy gut motility through regular exercise and stress management
  5. Supporting overall gut health with probiotics and prebiotics

Is it possible to completely prevent SIBO? While it may not be possible to completely prevent SIBO in all cases, especially for individuals with certain risk factors, adopting a healthy lifestyle and addressing underlying health issues can significantly reduce the risk of developing this condition.

In conclusion, Small Intestinal Bacterial Overgrowth (SIBO) is a complex digestive disorder that requires a comprehensive approach to diagnosis and treatment. By understanding its causes, symptoms, and management strategies, individuals can work with healthcare providers to effectively address SIBO and improve their overall digestive health. Ongoing research continues to shed light on this condition, promising improved diagnostic and treatment options in the future.

Small Intestinal Bacterial Overgrowth – PMC

1. Fine D, Schiller LR. American Gastroenterological Association Medical Position Statement. Guidelines for the evaluation and management of chronic diarrhea. Gastroenterology. 1999;116:1464–1486. [PubMed] [Google Scholar]

2. Corrazza GR, Menozzi MG, Strocchi A, et al. The diagnosis of small bowel bacterial overgrowth: reliability of jejunal culture and inadequacy of breath hydrogen testing. Gastroenterology. 1990;98:302–309. [PubMed] [Google Scholar]

3. Issacs PE, Kim YS. Blind loop syndrome and small bowel bacterial contamination. Clin Gastroenterol. 1983;12:395–414. [PubMed] [Google Scholar]

4. Bouhnik Y, Alain S, Attar A, et al. Bacterial populations contaminating the upper gut in patients with small intestinal bacterial overgrowth syndrome. Am J Gastroenterol. 1999;94:1327–1331. [PubMed] [Google Scholar]

5. Parlesak A, Klein B, Schecher K, et al. Prevalence of small bowel bacterial overgrowth and its association with nutrition intake in nonhospitalized older adults. J Am Geriatr Soc. 2003;51:768–773. [PubMed] [Google Scholar]

6. Mitsui T, Kagami H, Kinomoto H, et al. Small bowel bacterial overgrowth and rice malabsorption in healthy and physically disabled older adults. J Hum Nutr Dietet. 2003;16:119–122. [PubMed] [Google Scholar]

7. Teo M, Chung S, Chitti L, et al. Small bowel bacterial overgrowth is a common cause of chronic diarrhea. J Gastro Hepatol. 2004;19:904–909. [PubMed] [Google Scholar]

8. Lewis SJ, Potts LF, Malhotra R, et al. Small bowel bacterial overgrowth in subjects living in residential care homes. Age Ageing. 1999;28:181–185. [PubMed] [Google Scholar]

9. Pimentel M, Chow EJ, Lin HC. Normalization of lactulose breath testing correlates with symptom improvement in irritable bowel syndrome: a double-blind, randomized, placebo-controlled study. Am J Gastroenterol. 2003;98:412–419. [PubMed] [Google Scholar]

10. Riordan SM, McIver CJ, Wakefield D, et al. Small intestinal mucosal immunity and morphometry in luminal overgrowth of indigenous gut flora. Am J Gastroenterol. 2001;96:494–500. [PubMed] [Google Scholar]

11. Haboubi NY, Lee GS, Montgomery RD. Duodenal mucosal morphometry of elderly patients with small intestinal bacterial overgrowth: Response to antibiotics treatment. Age Ageing. 1991;20:29–32. [PubMed] [Google Scholar]

12. Saltzman JR, Kowdley KV, Pedrosa MC, et al. Bacterial overgrowth without clinical malabsorption in elderly hypochlorhydric subjects. Gastroenterology. 1994;106:615–623. [PubMed] [Google Scholar]

13. Husebye E, Skar V, Hoverstad T, et al. Fasting hypochlorhydria with gram positive gastric flora is highly prevalent in healthy old people. Gut. 1992;33:1331–1337. [PMC free article] [PubMed] [Google Scholar]

14. Iivonen MK, Ahola TO, Matikainen MJ. Bacterial overgrowth, intestinal transit, and nutrition after total gastrectomy. Scan J Gastroenterol. 1998;33:63–70. [PubMed] [Google Scholar]

15. Brandi G, Biavati B, Calabrese C, et al. Urease-positive bacteria other than Helicobacter pylori in human gastric juice and mucosa. Am J Gastroenterol. 2006;101:1756–1761. [PubMed] [Google Scholar]

16. Shindo K, Fukumura M. Effect of h3-receptor antagonists on bile acid metabolism. J Investig Med. 1995;43:170–177. [PubMed] [Google Scholar]

17. Thorens J, Froehlich F, Schwizer W, et al. Bacterial overgrowth during treatment with omeprazole compared with cimetidine: a prospective randomised double blind study. Gut. 1996;39:54–59. [PMC free article] [PubMed] [Google Scholar]

18. Lewis SJ, Franco S, Young G, et al. Altered bowel function and duodenal bacterial overgrowth in patients treated with omeprazole. Aliment Pharmacol Ther. 1996;10:557–561. [PubMed] [Google Scholar]

19. Vantrappen G, Janssens J, Hellemans J, et al. The interdigestive motor complex of normal subjects and patients with bacterial overgrowth of the small intestine. J Clin Invest. 1977;59:1158–1166. [PMC free article] [PubMed] [Google Scholar]

20. Stotzer PO, Bjornsson ES, Abrahamsson H. Interdigestive and postprandial motility in small-intestinal bacterial overgrowth. Scan J Gastroenterol. 1996;31:875–880. [PubMed] [Google Scholar]

21. Husebye E, Skar V, Hoverstad T, et al. Abnormal intestinal motor patterns explain enteric colonization with gram-negative bacilli in late radiation enteropathy. Gastroenterology. 1995;109:1078–1089. [PubMed] [Google Scholar]

22. Lacy BE, Koch KL, Crowell MD. Manometry. In: Schuster MM, Crowell MD, Koch KL, editors. Atlas of Gastrointestinal Motility. 2nd ed. Hamilton, B.C.: Decker; 2002. pp. 135–150. [Google Scholar]

23. Parkman HP, Hasler WL, Fisher RS. American Gastroenterological Association technical review on the diagnosis and treatment of gastroparesis. Gastroenterology. 2004;127:1592–1622. [PubMed] [Google Scholar]

24. Nieuwenhuijs VB, Verheem A, Van Duijvenbode-Beumer H, et al. The role of interdigestive small bowel motility in the regulation of gut microflora, bacterial overgrowth, and bacterial translocation in rats. Ann Surg. 1998;228:188–193. [PMC free article] [PubMed] [Google Scholar]

25. Gunnarsdottir SA, Sadik R, Shev S, et al. Small intestinal motility disturbances and bacterial overgrowth in patients with liver cirrhosis and portal hypertension. Am J Gastroenterol. 2003;98:1362–1370. [PubMed] [Google Scholar]

26. Strid H, Simren M, Stotzer PO, et al. Patients with chronic renal failure have abnormal small intestinal motility and a high prevalence of small intestinal bacterial overgrowth. Digestion. 2003;67:129–137. [PubMed] [Google Scholar]

27. Wegener M, Adamek RJ, Wedmann B, et al. Gastrointestinal transit through esophagus, stomach, small and large intestine in patients with progressive systemic sclerosis. Dig Dis Sci. 1994;39:2209–2215. [PubMed] [Google Scholar]

28. Kaye SA, Lim SG, Taylor M, et al. Small bowel bacterial overgrowth in systemic sclerosis: detection using direct and indirect methods and treatment outcome. Brit J Rheumatol. 1995;34:265–269. [PubMed] [Google Scholar]

29. Armbrecht U, Lundell L, Lindstedt G, et al. Causes of malabsorption after total gastrectomy with Roux-en-Y reconstruction. Acta Chir Scand. 1988;154:37–41. [PubMed] [Google Scholar]

30. Akhrass R, Yaffe MB, Fischer C, et al. Small-bowel diverticulosis: perceptions and reality. J Am Coll Surg. 1997;184:383–388. [PubMed] [Google Scholar]

31. Swan RW. Stagnant loop syndrome resulting from small-bowel irradiation injury and intestinal by-pass. Gynecol Oncol. 1974;8:441–445. [PubMed] [Google Scholar]

32. Castiglione F, Del Vecchio Blanco G, Rispo A, et al. Orocecal transit time and bacterial overgrowth in patients with Crohn’s disease. J Clin Gastroenterol. 2000;31:63–66. [PubMed] [Google Scholar]

33. Pignata C, Budillon G, Monaco G, et al. Jejunal bacterial overgrowth and intestinal permeability in children with immunodeficiency syndromes. Gut. 1990;31:879–882. [PMC free article] [PubMed] [Google Scholar]

34. Riordan SM, McIver CJ, Wakefield D, et al. Serum immunoglobulin and soluble IL-2 receptor levels in small intestinal overgrowth with indigenous gut flora. Dig Dis Sci. 1999;44:939–944. [PubMed] [Google Scholar]

35. Riordan SM, McIver CJ, Wakefield D, et al. Small intestinal bacterial overgrowth in the symptomatic elderly. Am J Gastroenterol. 1997;92:47–51. [PubMed] [Google Scholar]

36. McLoughlin GA, Hede JE, Temple JG, et al. The role of IgA in the prevention of bacterial colonization of the jejunum in the vagotomized subject. Br J Surg. 1978;65:435–437. [PubMed] [Google Scholar]

37. Wilcox CM, Waites KB, Smith PD. No relationship between gastric pH, small bowel bacterial colonization, and diarrhoea in HIV-1 infected patients. Gut. 1999;44:101–105. [PMC free article] [PubMed] [Google Scholar]

38. Lacy BE, DeLee R. Irritable Bowel Syndrome: A syndrome in evolution. J Clin Gastroenterol. 2005;39:S230–S242. [PubMed] [Google Scholar]

39. Pimentel M, Chow EJ, Lin HC. Eradication of small intestinal bacterial overgrowth reduces symptoms in irritable bowel syndrome. Am J Gastroenterol. 2000;95:3503–3506. [PubMed] [Google Scholar]

40. Nucera G, Gabrielli M, Lupascu A, et al. Abnormal breath tests to lactose, fructose, and sorbitol in irritable bowel syndrome may be explained by small intestinal bacterial overgrowth. Aliment Pharmacol Ther. 2005;21:1391–1395. [PubMed] [Google Scholar]

41. Parisi G, Leandro G, Bottona E, et al. Small intestinal bacterial overgrowth and irritable bowel syndrome [letter] Am J Gastroenterol. 2003;98:2572. [PubMed] [Google Scholar]

42. Walters B, Vanner SJ. Detection of bacterial overgrowth in IBS using the lactulose h3 breath test: Comparison with the 14C-d-xylose and healthy controls. Am J Gastroenterol. 2005:1566–1570. [PubMed] [Google Scholar]

43. Pimentel M, Sofler EE, Chow EJ, et al. Lower frequency of MMC is found in IBS subjects with abnormal lactulose breath test, suggesting bacterial overgrowth. Dig Dis Sci. 2002;47:2639–2643. [PubMed] [Google Scholar]

44. Virally-Monod M, Tielmans D, Kevorkian JP, et al. Chronic diarrhea and diabetes mellitus: prevalence of small intestinal bacterial overgrowth. Diabetes Metab. 1998;24:530–536. [PubMed] [Google Scholar]

45. Urita Y, Ishihara S, Akimoto T, et al. Seventy-five gram glucose tolerance test to assess carbohydrate malabsorption and small bowel bacterial overgrowth. World J Gastroenterol. 2006;12:3092–3095. [PMC free article] [PubMed] [Google Scholar]

46. Husebye E, Engedal K. The patterns of motility are maintained in the human small intestine throughout the process of aging. Scand J Gastroenterol. 1992;27:397–404. [PubMed] [Google Scholar]

47. Melkersson M, Andersson H, Bosaeus I, et al. Intestinal transit time in constipated and non-constipated geriatric patients. Scand J Gastroenterol. 1983;18:593–597. [PubMed] [Google Scholar]

48. Tursi A. Gastrointestinal motility disturbances in celiac disease. J Clin Gastroenterol. 2004;38:642–645. [PubMed] [Google Scholar]

49. Tursi A, Brandimarte G, Giorgetti GM. High prevalence of small intestinal bacterial overgrowth in celiac patients with persistence of gastrointestinal symptoms after gluten withdrawal. Am J Gastroenterol. 2003;98:839–843. [PubMed] [Google Scholar]

50. Deitch EA, Sittig K, Li M, et al. Obstructive jaundice promotes bacterial translocation from the gut. Am J Surg. 1990;159:79–84. [PubMed] [Google Scholar]

51. Madrid AM, Cumsille F, Defillippi C. Altered small bowel motility in patients with liver cirrhosis depends on severity of liver disease. Dig Dis Sci. 1997;42:738–742. [PubMed] [Google Scholar]

52. Chang CS, Chen GH, Lien HC, et al. Small intestine dysmotility and bacterial overgrowth in cirrhotic patients with spontaneous bacterial peritonitis. Hepatology. 1998;28:1187–1190. [PubMed] [Google Scholar]

53. Morencos FC, de las Heras Castano G, Martin Ramos L, et al. Small bowel bacterial overgrowth in patients with alcoholic cirrhosis. Dig Dis Sci. 1995;40:1252–1256. [PubMed] [Google Scholar]

54. Bauer TM, Steinbruckner B, Brinkmann FE, et al. Small intestinal bacterial overgrowth in patients with cirrhosis: prevalence and relation with spontaneous bacterial peritonitis. Am J Gastroenterol. 2001;96:2962–2967. [PubMed] [Google Scholar]

55. Bauer TM, Schwacha H, Steinbruckner B, et al. Small intestinal bacterial overgrowth in human cirrhosis is associated with systemic endotoxemia. Am J Gastroenterol. 2002;97:2364–2370. [PubMed] [Google Scholar]

56. Chang CS, Yang SS, Kao CH, et al. Small intestinal bacterial overgrowth versus antimicrobial capacity in patients with spontaneous bacterial peritonitis. Scand J Gastroenterol. 2001;36:92–96. [PubMed] [Google Scholar]

57. Li YF, Newton TJ, Weisbrodt NW, et al. Intestinal migrating myoelectrical complexes in rats with acute pancreatitis and bile duct ligation. J Surg Res. 1993;55:182–187. [PubMed] [Google Scholar]

58. Van Felius ID, Akkermans LMA, Bosscha K, et al. Interdigestive small bowel motility and duodenal bacterial overgrowth in experimental acute pancreatitis. Neurogastroenterol Motil. 2003;15:267–276. [PubMed] [Google Scholar]

59. Trespi E, Ferrieri A. Intestinal bacterial overgrowth during chronic pancreatitis. Curr Med Res Opin. 1999;15:47–52. [PubMed] [Google Scholar]

60. Hauge T, Persson J, Danielsson D. Mucosal bacterial growth in the upper gastrointestinal tract in alcoholics (heavy drinkers) Digestion. 1997;58:591–595. [PubMed] [Google Scholar]

61. Stotzer PO, Johansson C, Mellstrom D, et al. Bone mineral density in patients with small intestinal bacterial overgrowth. Hepatogastroenterology. 2003;50:1415–1418. [PubMed] [Google Scholar]

62. Saltzman JR, Russell RM. Nutritional consequences of intestinal bacterial overgrowth. Comp Ther. 1994;20:523–530. [PubMed] [Google Scholar]

63. Shindo K, Machinda M, Koide K, et al. Deconjugation ability of bacteria isolated from the jejunal fluid of patients with progressive systemic sclerosis and its gastric pH. Hepatogastroenterology. 1998;45:1643–1650. [PubMed] [Google Scholar]

64. Wanitschke R, Ammon HV. Effects of dihydroxy bile acids and hydroxyl fatty acids on the absorption of oleic acid in the human jejunum. J Clin Invest. 1978;61:178–186. [PMC free article] [PubMed] [Google Scholar]

65. Gianella RA, Rout WR, Toskes PP. Jejunal brush border injury and impaired sugar and amino acid uptake in the blind loop syndrome. Gastroenterology. 1974;67:965–974. [PubMed] [Google Scholar]

66. King CE, Toskes PP. Protein-losing enteropathy in the human and experimental rat blind-loop syndrome. Gastroenterology. 1981;80:504–509. [PubMed] [Google Scholar]

67. Welkos SL, Toskes PP, Baer H. Importance of anaerobic bacteria in the cobalamin malabsorption of the experimental rat blind loop syndrome. Gastroenterology. 1981;80:313–320. [PubMed] [Google Scholar]

68. Suter PM, Golner BB, Goldin BR, et al. Reversal of protein-bound vitamin B12 malabsorption with antibiotics in atrophic gastritis. Gastroenterology. 1991;101:1039–1045. [PubMed] [Google Scholar]

69. Russell RM, Krasinski SD, Samloff IM, et al. Folic acid malabsorption in atrophic gastritis: Possible compensation by bacterial folate synthesis. Gastroenterology. 1986;91:1476–1482. [PubMed] [Google Scholar]

70. Camilo E, Zimmerman J, Mason JB, et al. Folate synthesized by bacteria in the human upper small intestine is assimilated by the host. Gastroenterology. 1996;110:991–998. [PubMed] [Google Scholar]

71. Romagnuolo J, Schiller, D, Bailey, RJ. Using breath tests wisely in a gastroenterology practice: an evidence-based review of indications and pitfalls in interpretation. Am J Gastroenterol. 2002;97:1113–1126. [PubMed] [Google Scholar]

72. Riordan SM, McIver CJ, Duncombe VM, et al. Evaluation of the rice breath hydrogen test for small intestinal bacterial overgrowth. Am J Gastroenterol. 2000;95:2858–2864. [PubMed] [Google Scholar]

73. King CE, Toskes PP, Guilarte TR, et al. Comparison of the one-gram d-[14C]xylose breath test to the [14C]bile acid breath test in patients with small-intestine bacterial overgrowth. Dig Dis Sci. 1980;25:53–58. [PubMed] [Google Scholar]

74. Swart GR, van den Berg JW. 13C breath tests in gastroenterological practice. Scand J Gastroenterol Suppl. 1998;225:13–18. [PubMed] [Google Scholar]

75. King CE, Toskes PP. Comparison of the 1 gram 14C-D-xylose, 10 gram lactulose and 80 gram glucose h3 breath test in patients with small intestinal bacterial overgrowth. Gastroenterology. 1986;91:1447–1451. [PubMed] [Google Scholar]

76. Fromm H, Hofmann AF. Breath test for altered bile-acid metabolism. Lancet. 1971;2:621–625. [PubMed] [Google Scholar]

77. Suhr O, Danielsson A, Horstedt P, et al. Bacterial contamination of the small bowel evaluated by breath tests, 75Se-labelled homocholic-tauro acid, and scanning electron microscopy. Scan J Gastroenterol. 1990;25:841–852. [PubMed] [Google Scholar]

78. Gibson GR, Cummings JH, Macfarlane GT, et al. Alternative pathways for hydrogen disposal during fermentation in the human colon. Gut. 1990;31:679–683. [PMC free article] [PubMed] [Google Scholar]

79. Bjorneklett A, Fausa O, Midvedt T. Small-bowel bacterial overgrowth in the postgastrectomy syndrome. Scan J Gastroenterol. 1983;18:277–287. [PubMed] [Google Scholar]

80. Salzberg DM, Levine GM, Lubar C. Impact of age, sex, race, and functional complaints on hydrogen (h3) production. Dig Dis Sci. 1988;33:308–314. [PubMed] [Google Scholar]

81. Hutchinson S, Logan R. The effect of long-term omeprazole on the glucosehydrogen breath test in elderly patients. Age Ageing. 1997;26:87–89. [PubMed] [Google Scholar]

82. Kerlin P, Wong L. Breath hydrogen testing in bacterial overgrowth of the small intestine. Gastroenterology. 1988;95:982–988. [PubMed] [Google Scholar]

83. Walters B, Vanner SJ. Detection of bacterial overgrowth in IBS using the lactulose breath test: comparison with 14C-D-xylose and healthy controls. Am J Gastroenterol. 2005;100:1566–1570. [PubMed] [Google Scholar]

84. Rumessen JJ, Gudmand-Hoyer E, Bachmann E, et al. Diagnosis of bacterial overgrowth of the small intestine. Comparison of the 14C-D-xylose breath test and jejunal cultures in 60 patients. Scand J Gastroenterol. 1985;20:1267–1275. [PubMed] [Google Scholar]

85. Stotzer PO, Kilander AF. Comparison of the 1-gram 14C-D-xylose breath test and the 50-gram hydrogen glucose breath test for diagnosis of small intestinal bacterial overgrowth. Digestion. 2000;61:165–171. [PubMed] [Google Scholar]

86. Goshal UC, Goshal U, Das K, et al. Utility of hydrogen breath tests in diagnosis of small intestinal bacterial overgrowth in malabsorption syndrome, and its relationship with oro-cecal transit time. Indian J Gastroenterol. 2006;25:6–10. [PubMed] [Google Scholar]

87. Riordan SM, McIver CJ, Walker BM, et al. The lactulose breath hydrogen test and small intestinal bacterial overgrowth. Am J Gastroenterol. 1996;91:1795–1803. [PubMed] [Google Scholar]

88. Chang CS, Chen GH, Kao CH, et al. Increased accuracy of the carbon-14 Dxylose breath test in detecting small-intestinal bacterial overgrowth by correction with the gastric emptying rate. Eur J Nucl Med. 1995;22:1118–1122. [PubMed] [Google Scholar]

89. Perman JA, Modler S, Barr RG, et al. Fasting breath hydrogen concentration: normal values and clinical application. Gastroenterology. 1984;87:1358–1363. [PubMed] [Google Scholar]

90. Madrid AM, Hurtado C, Venegas M, et al. Long-term treatment with cis-apride and antibiotics in liver cirrhosis: effect on small intestinal motility, bacterial overgrowth, and liver function. Am J Gastroenterol. 2001;96:1251–1255. [PubMed] [Google Scholar]

91. Edmunds MC, Chen JD, Soykan I, et al. Effect of octreotide on gastric and small bowel motility in patients with gastroparesis. Aliment Pharmacol Ther. 1998;12:167–174. [PubMed] [Google Scholar]

92. Soudah HC, Hasler WL, Owyang C. Effect of octreotide on intestinal motility and bacterial overgrowth in scleroderma. N Engl J Med. 1991;325:1461–1467. [PubMed] [Google Scholar]

93. Bishop WP. Breath hydrogen testing for small bowel bacterial overgrowth– a lot of hot air? J Pediatr Gastroenterol Nutr. 1997;25:245–246. [PubMed] [Google Scholar]

94. Di Stefano M, Miceli E, Missanelli A, et al. Absorbable vs. non-absorbable antibiotics in the treatment of small intestine bacterial overgrowth in patients with blind-loop syndrome. Aliment Pharmacol Ther. 2005;21:985–992. [PubMed] [Google Scholar]

95. Di Stefano M, Malservisi S, Veneto G, et al. Rifaximin versus chlortetracycline in the short-term treatment of small intestinal bacterial overgrowth. Aliment Pharmacol Ther. 2000;14:551–556. [PubMed] [Google Scholar]

96. Castiglione F, Rispo A, Di Girolamo E, et al. Antibiotic treatment of small bowel bacterial overgrowth in patients with Crohn’s disease. Aliment Pharmacol Ther. 2003;18:1107–1112. [PubMed] [Google Scholar]

97. Attar A, Flourie B, Rambaud JC, et al. Antibiotic efficacy in small intestinal bacterial overgrowth-related chronic diarrhea: a crossover, randomized trial. Gastroenterology. 1999;117:794–797. [PubMed] [Google Scholar]

98. Pimentel M, Chow EJ, Lin HC. Normalization of lactulose breath testing correlates with symptom improvement in irritable bowel syndrome. a double-blind, randomized, placebo-controlled study. Am J Gastroenterol. 2003;92:412–419. [PubMed] [Google Scholar]

99. Pimentel M, Park S, Mirocha J, et al. The effect of a nonabsorbed oral antibiotic (Rifaxamin) on the symptoms of the irritable bowel syndrome. Ann Intern Med. 2006;145:557–563. [PubMed] [Google Scholar]

100. Gaon D, Garmendia C, Murrielo NO, et al. Effect of Lactobacillus strains (L. casei and L. Acidophillus Strains cerela) on bacterial overgrowth-related chronic diarrhea. Medicina. 2002;62:159–163. [PubMed] [Google Scholar]

101. Stotzer PO, Blomberg L, Conway PL, et al. Probiotic treatment of small intestinal bacterial overgrowth by Lactobacillus fermentum KLD. Scand J Infect Dis. 1996;28:615–619. [PubMed] [Google Scholar]

Small bowel bacterial overgrowth Information | Mount Sinai

Overgrowth – intestinal bacteria; Bacterial overgrowth – intestine; Small intestinal bacterial overgrowth; SIBO





Small bowel bacterial overgrowth is a condition in which very large numbers of bacteria grow in the small intestine.

























The small intestine is the portion of the digestive system most responsible for absorption of nutrients from food into the bloodstream. The pyloric sphincter governs the passage of partly digested food from the stomach into the duodenum. This short first portion of the small intestine is followed by the jejunum and the ileum. The ileocecal valve of the ileum passes digested material into the large intestine.


Causes

Most of the time, unlike the large intestine, the small intestine does not have a large number of bacteria. Excess bacteria in the small intestine may use up the nutrients needed by the body. As a result, a person may become malnourished.

The breakdown of nutrients by the excess bacteria can also damage the lining of the small intestine. This can make it even harder for the body to absorb nutrients.

Conditions that can lead to overgrowth of bacteria in the small intestine include:

  • Complications of diseases or surgery that create pouches or blockages in the small intestine. Crohn disease is one of these conditions.
  • Diseases that lead to decreased movement of the small bowel, such as diabetes and scleroderma.
  • Immunodeficiency, such as AIDS or immunoglobulin deficiency.
  • Short bowel syndrome caused by surgical removal of the small intestine.
  • Small bowel diverticulosis, in which small, or, at times, large sacs occur in the wall of the intestine. These sacs allow too many bacteria to grow.
  • Surgical procedures that create a loop of small intestine where excess bacteria can grow. An example is a Billroth II type of stomach removal (gastrectomy).
  • Some cases of irritable bowel syndrome (IBS).












Symptoms

The most common symptoms are:

  • Abdominal fullness
  • Abdominal pain and cramps
  • Bloating
  • Diarrhea (most often watery)
  • Gassiness

Other symptoms may include:

  • Fatty stool
  • Weight loss












Exams and Tests

Your health care provider will perform a physical exam and ask about your medical history. Tests may include:

  • Blood chemistry tests (such as albumin level)
  • Complete blood count (CBC)
  • Fecal fat test
  • Small intestine endoscopy
  • Vitamin levels in the blood
  • Small intestine biopsy or culture
  • Special breath tests












Treatment

The goal is to treat the cause of the bacterial overgrowth. Treatment may include:

  • Antibiotics
  • Medicines that speed intestinal movement
  • Intravenous (IV) fluids
  • Nutrition given through a vein (total parenteral nutrition or TPN) in a malnourished person

A lactose-free diet can be helpful.












Possible Complications

Severe cases lead to malnutrition. Other possible complications include:

  • Dehydration

  • Excess bleeding or other problems due to vitamin deficiency

  • Liver disease

  • Osteomalacia or osteoporosis

  • Inflammation of the intestine










Lacy BE, DiBaise JK. Small intestinal bacterial overgrowth. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran’s Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 105.

Manolakis CS, Rutland TJ, Di Palma JA. Small intestinal bacterial overgrowth. In: McNally PR, ed. GI/Liver Secrets Plus. 5th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 44.

Rej A, Chew TS, Sanders DS. Gastroenterology. In: Penman ID, Ralston SH, Strachan MWJ, Hobson RP, eds. Davidson’s Principles and Practice of Medicine. 24th ed. Philadelphia, PA: Elsevier; 2023:chap 23.

Sundaram M, Kim J. Short bowel syndrome. In: Yeo CJ, ed. Shackelford’s Surgery of the Alimentary Tract. 8th ed. Philadelphia, PA: Elsevier; 2019:chap 79.

Last reviewed on: 5/4/2022

Reviewed by: Michael M. Phillips, MD, Emeritus Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.


Small Intestinal Bacterial Overgrowth Syndrome

Description

Small intestinal bacterial overgrowth (SIBO = small intestinal bacterial overgrowth) does not cause organ damage or affect life expectancy.

However

  • chronic digestive problems,
  • increased flatulence,
  • feeling of heaviness in the stomach,
  • colicky abdominal pain,
  • violation of resorption in the intestine

have a negative impact on the quality of life of the patient.

The small intestine is normally inhabited by a small number of bacteria, approximately 103-104 microorganisms/ml. Gastric acid destroys most of the bacteria that enter with food, so food microorganisms are found in small quantities in the small intestine. In contrast, the intestinal flora of the large intestine contains millions of times more bacteria – approximately 1010-1012 microorganisms / ml. They have a physiological function: in the process of fermentation, they break down food already digested in the small intestine. Peristaltic contractions and the ileocecal valve protect the small intestine from colonic flora. Additional protection against the reproduction of bacteria is provided by immunoglobulins of the mucous membrane of the small intestine and the bacteriostatic properties of the secret of the pancreas and bile.

Symptoms

Pressure on the stomach causes nausea and heartburn. Gas formation leads to distension of the small intestine with spasmodic pains in the abdomen, especially in the navel and its lower right part. In this case, both low peristalsis with constipation and more active peristalsis, leading to diarrhea, occur. With such an accelerated passage, fats, iron and vitamin B12 are less absorbed, so the stool becomes fatty, weight loss, hypovitaminosis and other deficiency states occur. As soon as the gases enter the large intestine, they collect in flexures and cause pain under the costal arches on both sides. Pressure on the diaphragm can cause complaints in the area of ​​the heart, heart rhythm disturbances and shortness of breath. It may also worsen the condition of the skin. In general, with chronic digestive problems, a person experiences poor overall health, sometimes leading to depressive disorders. A state of extreme fatigue may occur.

Causes and Risks

The discomfort of bacterial overgrowth in the small intestine is caused by the fact that the incompletely digested food mixture begins to be decomposed by bacteria approximately 30-90 minutes after ingestion. This increases the production of gases. Due to the siphon-like transition from the duodenum to the jejunum, gases can hardly find their way up, leading to a feeling of fullness and bloating, as well as belching and bad breath.

A special form of bacterial overgrowth in the small intestine is the “blind loop syndrome”, in which, after surgery on the intestine, a significant overgrowth of bacteria occurs in a functionally disabled area of ​​the intestine.

Examination and diagnosis

Diagnosis of bacterial overgrowth syndrome in the small intestine is established using a hydrogen breath test with lactose or glucose. Both of these tests are easily tolerated. After the patient has drunk the sugar solution, the hydrogen content in the air exhaled by him is measured four times (in the test with lactose, the blood sugar content is additionally measured). An increased hydrogen indicator indicates excessive gas formation. If lactose is used in the test, then the patient can be simultaneously tested for lactose intolerance. Along with a breath test, a microbiological examination of the secretion of the jejunum can also be carried out. The evidence of violation is the number of microorganisms above 105/ml.

Differential diagnosis should exclude other, primarily oncological diseases of the alimentary tract, which can also be accompanied by bacterial overgrowth. In the presence of the above symptoms, additional examinations should be performed, including gastroscopy (to detect Helicobacter and celiac disease), histology for atrophic gastritis, coloscopy (in order to exclude malignant or inflammatory stenoses, fistulas and diverticula), ultrasound examination of the abdominal cavity, and in case of insufficient recognition – magnetically – resonant examination. Diseases that promote bacterial overgrowth in the small intestine, especially cirrhosis of the liver, diabetes, and AIDS, must be ruled out by laboratory testing. Additional breath tests will help identify possible lactose or fructose intolerance. The stool should also be examined for the presence of elastase (which may indicate insufficient pancreatic function) and pathological microorganisms and parasites. Long-term use of gastric acid-blocking drugs can also contribute to bacterial overgrowth in the small intestine.

Treatment

For the treatment of bacterial overgrowth in the small intestine, the nonabsorbable antibiotic Rifaximin or, alternatively, co-Trimoxazole or Metronidazole is recommended. Additionally, you can take probiotics, such as yeast. If the bacterial overgrowth is the result of another underlying disease, then treatment should begin with its elimination. In a state of insufficiency, appropriate replacement therapy is necessary.

Course of illness and prognosis

Small intestinal bacterial overgrowth syndrome is a disease with a good prognosis; however, if the cause that led to its occurrence and development is not eliminated, the disease may recur.

Bacterial overgrowth syndrome / Diseases / Clinic EXPERT

Bacterial overgrowth syndrome (SIBO) is a pathological condition characterized by an increase in the number of bacteria in the small intestine with the development of diarrheal syndrome and malabsorption of certain nutrients.

This condition/disease in the domestic literature is often called a special case of intestinal dysbacteriosis/dysbiosis.

The prevalence of SIBO

The prevalence of this syndrome in the world remains unknown. In the literature, the incidence of SIBO is most often assessed in various diseases of the gastrointestinal tract (GIT) and other organs. In particular, it is known that SIBO occurs in 38% of patients with irritable bowel syndrome and in 50-60% of patients with liver cirrhosis. Often, this pathological syndrome is detected in people suffering from inflammatory bowel diseases, systemic connective tissue diseases (for example, scleroderma), endocrine pathologies (diabetes mellitus), etc.

Causes and mechanisms of development of SIBO

Normally, different sections of the digestive tube have different species and quantitative composition of microorganisms inhabiting them. So, for example, in the stomach and upper parts of the small intestine, the microbial composition is rather poor, limited to a small (10 3 -10 4 colony-forming units (CFU) per milliliter of aspirate) number of bacteria, among which lactobacilli, enterococci and some other aerobic bacteria predominate. bacteria.

In the terminal parts of the small intestine, especially in the terminal ileum, the number and variety of microorganisms is growing. In this transition zone between the small and large intestine, the number of microorganisms increases to 10 7 -10 9 CFU/ml. The main bacteria found in this region are lacto- and bifidobacteria, streptococci, bacteroids, etc.

Finally, the large intestine is the place of “residence” of anaerobic bacteria that do not require oxygen for life (bacteroids, bifidobacteria, enterococci and clostridia, lactobacilli, E. coli, streptococci, staphylococci, etc.). The number of microorganisms in this section of the intestine is maximum and can reach 10 12 cfu/ml.

Quantitative and qualitative microbial composition in different parts of the gastrointestinal tract is maintained by several mechanisms. This is the acidic environment of the stomach, and the bactericidal action of bile in the small intestine, as well as the intact motility of the stomach and intestines. Very important is the normal motor and closure function of the gastrointestinal sphincters, such as the pyloric sphincter (valve between the stomach and duodenum 12) and the ileocecal valve (between the ileum and colon).

Violation of this regulation leads to the fact that increases the number of microorganisms in the small intestine, and this leads to various digestive disorders. This condition is called SIBO or Small Intestine Bacterial Overgrowth Syndrome .

The main reasons for the development of SIBR :

  1. conditions leading to a decrease in hydrochloric acid products in the stomach are hypo- and ahlorhydria against the background of atrophic or autoimmune gastritis, due to the use of drugs from the H3-hystaminoblocator group and proton pump inhibitors;
  2. Impaired motility of the stomach and / or small intestine – often observed in diabetes mellitus, cirrhosis of the liver, chronic renal failure, scleroderma, polymyositis, celiac disease, Crohn’s disease, etc. ;
  3. Anatomical disorders – consequences of surgical interventions (resection of the stomach, ileocecal valve, etc.), diverticula of the small intestine, stricture of the small intestine of any origin, etc.;
  4. Use of antibiotics, non-steroidal anti-inflammatory drugs, cytostatics, steroid hormones, tricyclic antidepressants, opiates, etc.;
  5. Immune disorders, including deficiency of secretory immunoglobulin A;
  6. Chronic pancreatitis with exocrine pancreatic insufficiency;
  7. Chronic alcohol abuse;
  8. Old age and senility increase the risk of SIBO.

An increase in the number of small intestinal microorganisms results in:

  • a decrease in the content and activity of intraluminal and parietal enzymes due to their destruction by bacteria;
  • insufficient breakdown of nutrients, impaired absorption and increase in the liquid part of the intestinal contents with the development of diarrhea;
  • premature deconjugation of bile acids in the early parts of the small intestine with the development of chemical damage to the small intestine mucosa and diarrhea.

Due to malabsorption in the small intestine, a deficiency of certain micro and macro elements, as well as vitamins (for example, vitamin B12), develops.

Symptoms of SIBO

  • Bloating and/or flatulence is the most common symptom;
  • Loose stool – from mushy 1-2 times a day to liquid several times a day;
  • Constipation – rare but does not rule out SIBO;
  • Mild abdominal pain (often associated with increased gas formation) – usually localized in the umbilical region;
  • Feeling of “transfusion” or rumbling in the abdomen;
  • Weight loss – possible with severe and prolonged SIBO;
  • Various complaints due to deficiency of micro-, macroelements and vitamins.

Diagnosis of SIBO

The typical clinical presentation of the disease and history (for example, an indication of the use of antibiotics) suggest the diagnosis of SIBO. The results of additional tests serve as confirmation.

Due to the fact that SIBO is associated with an increase in the number of bacteria in the small intestine, the use of traditional in our country fecal analysis for dysbiosis/dysbacterosis for the diagnosis of this syndrome has no value . In the study of the bacterial composition of feces, this method evaluates samples of fecal masses from the large intestine. The analysis includes the determination of only 20 varieties of bacteria, while more than 1000 have been isolated in the human intestine.

For scientific purposes and large medical centers, liquid contents (aspirate) of the duodenum are used for diagnosis. This aspirate can be plated on special media to detect aerobic and anaerobic bacteria and determine the number of CFU. An alternative is the polymerase chain reaction (PCR) method, which also determines the quantity (less often the qualitative composition) of small intestinal bacteria and other microorganisms.

According to the most recent recommendations, when the number of microorganisms in the aspirate from the small intestine is more than 10 3 CFU / ml, the probability of SIBO is high. Alas, the proposed research methods are expensive and cannot be used in routine practice.

If the quantitative characteristics of SIBO are more or less clear, then the qualitative changes in the bacterial composition of the small intestine in this condition remain poorly understood. There is only a small number of works in some diseases (for example, in irritable bowel syndrome), where certain changes in the proportions of some groups of bacteria to others . The clinical significance of these changes is still unclear.

Currently, most recommendations suggest using either a lactulose or glucose hydrogen breath test to diagnose SIBO. Normally, hydrogen is produced only by intestinal bacteria during the processing of certain carbohydrates. The resulting hydrogen is absorbed into the bloodstream, reaches the lungs and can be determined by a special analyzer in the exhaled air. The test evaluates the change in hydrogen concentration after ingestion of a carbohydrate solution. The non-absorbable carbohydrate lactulose is most often used as a test substrate, glucose is less commonly used.

In some individuals, SIBO symptoms may be due to overgrowth of methane-producing microorganisms, in which case a methane breath test may be used.

Other breath tests exist but are not routinely available.

Treatment of SIBO

Currently, SIBO is considered as a secondary condition that occurs as a result of an existing “background” disease or external influence (including drug therapy). Therefore, in all recommendations for the treatment of SIBO, treatment of the underlying disease is in the first place to prevent the recurrence of complaints.

One of the main methods of treatment for SIBO is the so-called “sanation” of the intestine by prescribing antibiotics. Preference is given to non-absorbable antibiotics (eg, rifaximin) and other antibacterial drugs that have proven effective.

Diet therapy that restricts foods rich in fermentable carbohydrates (called the lowFODMAP diet) may be effective in some patients.