Learn About Small Bowel Bacterial Overgrowth

What is the definition of Small Bowel Bacterial Overgrowth?

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

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What are the alternative names for Small Bowel Bacterial Overgrowth?

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

What are the causes of Small Bowel Bacterial Overgrowth?

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 movement problems in 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, and at times large sacs occur in the inner lining of the intestine. These sacs allow too many bacteria to grow. These sacs are much more common in the large bowel.
  • 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).
What are the symptoms of Small Bowel Bacterial Overgrowth?

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
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What are the current treatments for Small Bowel Bacterial Overgrowth?

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 – TPN) in a malnourished person

A lactose-free diet can be helpful.

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What are the possible complications of Small Bowel Bacterial Overgrowth?

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
Small intestine
What are the latest Small Bowel Bacterial Overgrowth Clinical Trials?
The Role of Breath Testing in Enriching the Likelihood of Response to Rifaximin in Patients With Diarrhea IBS
Summary: The purpose of this study is to learn more about how to improve treatment of patients with diarrhea predominant Irritable Bowel Syndrome (IBS-D) symptoms.Included patients will be requested to answer online surveys and will undergo treatment with rifaximin. Hydrogen breath testing and biologic samples collection will also be completed during the study.
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A Randomized Open Label Trial Evaluating the Efficacy of AEMCOLO (Rifamycin SV MMX) in the Treatment of Small Intestinal Bacterial Overgrowth (SIBO)
Summary: Open label interventional randomized pilot study utilizing two dosing regimens of AEMCOLO. The goal of this study is to evaluate effectiveness of a novel antibiotic, AEMCOLO (Rifamycin SV MMX) in the treatment of Small intestinal bacterial overgrowth (SIBO).
What are the Latest Advances for Small Bowel Bacterial Overgrowth?
Efficacy of an Irritable Bowel Syndrome Diet in the Treatment of Small Intestinal Bacterial Overgrowth: A Narrative Review.
Summary: Efficacy of an Irritable Bowel Syndrome Diet in the Treatment of Small Intestinal Bacterial Overgrowth: A Narrative Review.
Effect of Compound Lactic Acid Bacteria Capsules on the Small Intestinal Bacterial Overgrowth in Patients with Depression and Diabetes: A Blinded Randomized Controlled Clinical Trial.
Summary: Effect of Compound Lactic Acid Bacteria Capsules on the Small Intestinal Bacterial Overgrowth in Patients with Depression and Diabetes: A Blinded Randomized Controlled Clinical Trial.
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Incidence, Diagnosis and Management of Malabsorption Following Oesophagectomy: a Systematic Review.
Summary: Incidence, Diagnosis and Management of Malabsorption Following Oesophagectomy: a Systematic Review.
Who are the sources who wrote this article ?

Published Date: May 27, 2020
Published By: Jenifer K. Lehrer, MD, Department of Gastroenterology, Aria - Jefferson Health Torresdale, Jefferson Digestive Diseases Network, Philadelphia, PA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

What are the references for this article ?

El-Omar E, McLean MH. Gastroenterology. In: Ralston SH, Penman ID, Strachan MWJ, Hobson RP, eds. Davidson's Principles and Practice of Medicine. 23rd ed. Philadelphia, PA: Elsevier; 2018:chap 21.

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.

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.