Small bowel bacterial overgrowth is a syndrome that involves excessive numbers of bacteria growing in the small intestines. The large numbers of bacteria 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
• Irritable bowel syndrome
• Alcohol use
• Ileus
• Prolonged use of medicines called proton pump inhibitors or H2 blockers, which supress stomach acid secretion
• 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.

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
• Weight loss
• Fatty, floating stool

The goal is to treat the underlying 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 administered intravenously.

Severe cases lead to malnutrition. Other possible complications include:

• Dehydration
• Toxic megacolon
• Liver disease
• Osteoporosis