Small bowel bacterial overgrowth syndrome

Small Bowel Bacterial Overgrowth Syndrome
Other names	SIBO, Small Intestinal Bacterial Overgrowth
Specialty	Gastroenterology

Small Bowel Bacterial Overgrowth Syndrome (SIBO), also known as Small Intestinal Bacterial Overgrowth, is a disorder of excessive bacterial growth in the small intestine. Unlike the colon, which is rich with bacteria, the small intestine usually has fewer bacterial organisms. The excessive bacterial presence in the small intestine can lead to symptoms and is associated with various diseases including irritable bowel syndrome and celiac disease.

Causes

SIBO is typically caused by an abnormality of the normal movements of the stomach and small intestine, which can lead to an accumulation of bacteria. These abnormalities may be due to structural issues such as intestinal obstructions or motility disorders like diabetes mellitus and scleroderma. Other risk factors include:

• Gastrectomy or other surgeries that alter the gastrointestinal tract
• Recurrent use of antibiotics
• Immunodeficiency

Symptoms

Common symptoms of SIBO include:

• Abdominal pain
• Bloating
• Diarrhea
• Malnutrition
• Weight loss
• Fatigue

The symptoms of SIBO can be nonspecific and can mimic other conditions, making diagnosis challenging.

Diagnosis

Diagnosis of SIBO is primarily made through the use of a hydrogen breath test, which measures the amount of hydrogen in the breath after the patient consumes a sugar solution. Elevated levels of hydrogen indicate bacterial overgrowth. Other methods include:

• Jejunal aspirate and culture
• Blood tests to check for nutritional deficiencies

Treatment

Treatment for SIBO typically involves:

• Antibiotics to reduce bacterial overgrowth
• Nutritional support to address deficiencies
• Prokinetics to improve gut motility

Long-term management may require attention to diet, including possible adjustments to intake of fiber, lactose, and fructose.

Prognosis

With appropriate treatment, the prognosis for SIBO is generally good, though recurrence is common. Ongoing management strategies are often necessary to prevent relapse.

Epidemiology

The prevalence of SIBO in the general population is not well-defined, but it is known to be more common in older adults and those with underlying gastrointestinal disorders.