Definition

Small bowel bacterial overgrowth is a syndrome that involves very large numbers of bacteria growing in the small intestines.

Alternative Names

Overgrowth - intestinal bacteria; Bacterial overgrowth - intestine

Causes, incidence, and risk factors

The abnormally large numbers of bacteria in the small intestine compete for nutrients with the person who has the condition. As a result, the person with the condition may not absorb enough nutrients.

In addition, the breakdown of nutrients by the bacteria in the small intestines can damage the cells lining the intestinal wall.

Intestinal bacteria overgrowth can be seen with many different disorders, including:

• Surgical procedures -- for example, a Billroth II type of gastrectomy can block the duodenum and jejunum, causing intestinal bacterial overgrowth
• Short bowel syndrome
• Diseases that slow small bowel movement, such as diabetes and scleroderma
• Small bowel diverticulosis -- small protruding sacs of the inner lining of the intestine; although these sacs can happen anywhere along the intestinal tract, they are more common in the large bowel than the small bowel.
• Complications of diseases or surgery that create blind pouches or obstructions in the small bowel, such as Crohn's disease, Billroth II gastrectomy, and small bowel diverticulosis
• Diseases such as chronic pancreatitis, cirrhosis of the liver, alcoholism, and end-stage renal disease
• Immunodeficiency, such as AIDS

Symptoms

The most common symptoms are abdominal pain and cramps, fullness, bloating, and diarrhea. The diarrhea can be watery or bloody. Other symptoms may include:

• Anemia (low levels of red blood cells)
• Weight loss
• Fatty, floating stool

Signs and tests

Treatment

The goal is to treat the cause of the intestinal bacterial overgrowth. For certain conditions, antibiotics, anti-motility drugs, or hormones may be considered.

Treatment also involves getting enough fluids and nutrition.

If the person is already dehydrated, he or she may need intravenous (IV) fluids in a hospital. And, if already malnourished, total parenteral nutrition (TPN) may be necessary. TPN is nutrition (food) given through a vein.

Support Groups

Expectations (prognosis)

Complications

Severe cases lead to malnutrition. Other possible complications include:

• Dehydration
• Toxic megacolon
• Liver disease
• Osteoporosis

Calling your health care provider

Prevention

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