Health Information

Small Bowel Bacterial Overgrowth

(SBBO; Bacterial Overgrowth, Small Bowel; Small Intestine Bacterial Overgrowth; SIBO; Bacterial Overgrowth, Small Intestine)

Small bowel bacterial overgrowth (SBBO) occurs when there is a build-up of too much bacteria in the small bowel.

The Small Intestines

Causes

SBBO is often caused by an abnormality in the small bowel. Food is not able to flow properly though the intestines. Conditions that may cause this include:

Birth defect
Injury
Surgery
Conditions (eg, digestive disorder)

Risk Factors

Examples of conditions that may increase the risk of SBBO include:

Crohn’s disease
Irritable bowel syndrome (IBS)
Short bowel syndrome
Diverticulitis
Intestinal stricture (narrowing in the small intestine)
Digestive disorders (eg, celiac disease, lactose intolerance)
Blind loop syndrome (when part of the intestine is bypassed)
Intestinal infection (eg, food poisoning, traveler’s diarrhea)
Cirrhosis
Diabetes
Chronic pancreatitis
End-stage kidney or liver disease

Other risk factors include:

Intestinal surgery (eg, removal of part of the small intestine)
An obstruction in the small intestine
Weakened immune system
Being elderly (more likely to have conditions like diverticulitis)

Any condition that affects how food moves through the small bowel may increase the risk of SBBO.

Symptoms

Not all patients with SBBO will have symptoms. But symptoms may include:

Abdominal pain
Bloating and gas
Feeling of fullness
Constipation or diarrhea
Nutritional deficiencies (eg, vitamins B12, A, D, E, iron, thiamine)
Weight loss

Diagnosis

SBBO can be difficult to diagnose. The symptoms may be similar to other conditions. Your doctor will:

Ask about your symptoms and medical history
Do a physical exam
Order tests, such as:
- Blood tests to detects nutritional deficiencies (eg, anemia, B12 deficiency)
- Breath tests—involves fasting, eating some type of sugar, and then exhaling into a bag; the sample is analyzed to find out if there are levels of certain gases
- Culture of intestinal fluid (aspirate)—a catheter is used to get a sample of fluid from the small bowel

Treatment

The goals are to:

Reduce the levels of harmful bacteria in the small bowel
Treat the underlying condition

Medications

Antibiotics are often prescribed to treat SBBO. Usually treatment is temporary. But, in some cases, you may need to take antibiotics for a longer period.

Nutritional Support

To make sure that you get the proper nutrients, you may need to:

Work with a dietitian
Follow a special diet (eg, carbohydrate-restricted diet)
Take supplements (eg, iron, vitamin B12)
Take probiotics

In some cases, tube feeding is needed with a special formula.

Surgery

For severe cases, surgery may be needed. This is done to correct an abnormality in the small bowel.

Prevention

If you have any of the conditions that are linked to SBBO, get proper treatment. This may reduce your chance of having a build-up of bacteria in the small bowel.

RESOURCES:

American Gastroenterological Association

http://www.gastro.org/

National Digestive Diseases Information Clearinghouse

http://digestive.niddk.nih.gov/index.htm

CANADIAN RESOURCES:

Canadian Association of Gastroenterology

http://www.cag-acg.org/

Canadian Digestive Health Foundation

http://www.cdhf.ca/main.php/

References:

Aaron S. Malabsorption. EBSCO Health Library website. Available at: . Updated September 20, 2010. Accessed May 12, 2011.

Bacterial overgrowth syndrome. Merck Manual website. Available at: . Updated January 2008. Accessed May 12, 2011.

Bures J, Cyrany J, Kohoutova D, et al. Small intestinal bacterial overgrowth syndrome. World J Gastroenterol. 2010;16(24):2978–2990.

Dibaise J, Young R, Vanderhoof J. Enteric microbial flora, bacterial overgrowth, and short-bowel syndrome. University of South Alabama Gastroenterology Continuing Education website. Available at: . Published 2006. Accessed May 12, 2011.

Lactose and glucose hydrogen breath test. Cleveland Clinic website. Available at: . Updated November 25, 2008. Accessed May 12, 2011.

Lin H. Small intestinal bacterial overgrowth. JAMA. 2004;292(7):852-858.

McCoy K. Short bowel syndrome. EBSCO Health Library website. Available at: . Updated September 20, 2010. Accessed May 12, 2011.

Parrish C. Nutritional consequences of small intestinal bacterial overgrowth. University of Virginia, School of Medicine website. Available at: . Published December 2008. Accessed May 12, 2011.

Small bowel bacterial overgrowth—another cause for IBS symptoms. Tennessee Society of Gastroenterology Nurses and Associates website. Available at: . Accessed May 12, 2011.

Small bowel bacterial overgrowth overview. Cleveland Clinic website. Available at: . Accessed May 12, 2011.

Vanderhoof J, Young R. Bacterial overgrowth. The Oley Foundation website. Available at: . Accessed May 12, 2011.

Vanderhoof J, Young R, Murray N, Kaufman SS. Treatment strategies for small bowel bacterial overgrowth in short bowel syndrome. J Pediatr Gastroenterol Nutr. 1998;27(2):155-160.

Last reviewed June 2012 by Rosalyn Carson-DeWitt, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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