Small bowel bacterial overgrowth
Small bowel bacterial overgrowth is a condition in which very large numbers of bacteria grow in the small 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.
Malnourished
Malnutrition is the condition that occurs when your body does not get enough nutrients.
Read Article Now Book Mark ArticleThe 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.
Crohn disease
Crohn disease is a disease where parts of the digestive tract become inflamed. It most often involves the lower end of the small intestine and the be...
Read Article Now Book Mark Article - Diseases that lead to decreased movement of the small bowel, such as diabetes and scleroderma.
Diabetes
Diabetes is a long-term (chronic) disease in which the body cannot regulate the amount of sugar in the blood.
Read Article Now Book Mark ArticleScleroderma
Scleroderma is a disease that involves the buildup of fibrous tissue in the skin and elsewhere in the body. It also damages the cells that line the ...
Read Article Now Book Mark Article - Immunodeficiency, such as AIDS or immunoglobulin deficiency.
AIDS
Human immunodeficiency virus (HIV) is the virus that causes acquired immunodeficiency syndrome (AIDS). When a person becomes infected with HIV, the ...
Read Article Now Book Mark Article -
Short bowel syndrome caused by surgical removal of the small intestine.
Short bowel syndrome
Short bowel syndrome is a problem that occurs when part of the small intestine is missing or has been removed during surgery. Nutrients are not prop...
Read Article Now Book Mark Article - 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).
Gastrectomy
Gastrectomy is surgery to remove part or all of the stomach. If only part of the stomach is removed, it is called partial gastrectomyIf the whole sto...
Read Article Now Book Mark Article - 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)
CBC
A complete blood count (CBC) test measures the following:The number of white blood cells (WBC count)The number of red blood cells (RBC count)The numb...
Read Article Now Book Mark Article -
Fecal fat test
Fecal fat test
The fecal fat test measures the amount of fat in the stool. This can help gauge the percentage of dietary fat that the body does not absorb....
Read Article Now Book Mark Article - Small intestine endoscopy
Endoscopy
X-rays are a type of electromagnetic radiation, just like visible light. An x-ray machine sends individual x-ray waves through the body. The images...
Read Article Now Book Mark Article - 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
Dehydration
Dehydration occurs when your body does not have as much water and fluids as it needs. Dehydration can be mild, moderate, or severe, based on how much...
Read Article Now Book Mark Article - Excess bleeding or other problems due to vitamin deficiency
-
Liver disease
Liver disease
The term "liver disease" applies to many conditions that stop the liver from working or prevent it from functioning well. Abdominal pain or swelling...
Read Article Now Book Mark Article -
Osteomalacia or osteoporosis
Osteomalacia
Osteomalacia is softening of the bones. It most often occurs because of a problem with vitamin D, which helps your body absorb calcium. Your body n...
Read Article Now Book Mark ArticleOsteoporosis
Osteoporosis is a disease in which bones become fragile and more likely to break (fracture).
Read Article Now Book Mark Article - Inflammation of the intestine
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.
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.
Disclaimer