Small Bowel Bacterial Overgrowth

Small Bowel Bacterial Overgrowth (SIBO or SBBO)

What is small bowel bacterial overgrowth?

The small bowel connects to the stomach and the colon. The entire digestive tract contains bacteria with the majority in the large intestine (colon). The bacteria in the colon are different than the bacteria in the small bowel. The colon has at least 1,000,000,000 bacteria per milliliter. The small intestine has less than 10,000 bacteria per ml of fluid. When the bacteria count in the small intestine becomes greater than 100,000 per ml, the bacteria concentration becomes similar to the colon and can cause symptoms.

What causes small bowel bacterial overgrowth?

There are many conditions associated with small bowel bacterial overgrowth (SIBO). Diseases that alter the movement of the small bowel such as diabetes, prolonged illnesses, constipation, and partial or intermittent bowel obstruction (which cause intestine slow down and allow the bacteria to multiply and/or back up from the large intestine). Other associated conditions include small bowel diverticuli (out-pouching or pockets of the bowel wall which allow the bacteria to multiply inside of the pockets). Other conditions associated with SIBO include liver disease, chronic pancreatitis, and short bowel syndromes.

What are the symptoms of SIBO?

Symptoms commonly seen are excess gas, abdominal bloating and distension, diarrhea, dyspepsia, and abdominal pain. Additional symptoms include weight loss, constipation, malabsorption, and anemia.

Large numbers of gas producing bacteria can be present in the small intestine. The bacteria compete with the small intestine for the sugars and carbohydrates which produces large amounts of gas.

How is SIBO diagnosed?

SIBO is typically diagnosed using a Glucose Breath Test. This involves administering a single breath into a balloon every 15 minutes for 3 hours. After each balloon is filled, the patient ingests a small amount of sugar. The samples are analyzed for methane and hydrogen. Normally, people will absorb the glucose steadily as it passes through the small intestine. If the small bowel contains bacterial overgrowth, the bacteria produce a gas from the glucose and the gas is excreted in the breath.

Alternatively, your health care provider may also recommend an upper endoscopy to take a sample of the fluid contents from the small bowel (jejunal aspirate).

How is SIBO treated?

Diet: Your diet should include nutrients readily absorbed leaving fewer calories for the bacteria. The diet should be low in carbohydrates. The diet would be high in fat and low fiber. Lactase deficiency develops in many adults with SIBO. Avoiding lactose may help with symptoms.

Correct the underlying problem: If you have diabetes, control your blood sugars. If you are constipated, control your constipation.

Antibiotics: Antibiotic therapy may be beneficial. Response is measured by improvement of symptoms. Recurrence of SIBO may occur more frequently in the elderly, patients with prior appendectomy or on long term proton-pump inhibitor medications. Some patients require longer duration of therapy for 1 to 2 months or repeating therapy at regular intervals.

Probiotics: There have been limited studies with probiotics. Probiotics are live bacteria that, when ingested may result in a healthy benefit. Probiotics are bacteria that have been found in the small bowel. Commonly used probiotics for SIBO are VSL#3 or Flora-Q which are mixtures of several different bacterial species. There effectiveness has not been well studied.

When to seek medical advice for SIBO or associated symptoms.

You should be seek medical attention if you are loosing weight, having symptoms of nausea or vomiting, diarrhea or if symptoms are affecting you job or your daily life.


DISCLAIMER: PLEASE READ CAREFULLYThe information on this website is to provide general guidance. In no way does any of the information provided reflect definitive medical advice and self diagnoses should not be made based on information obtained online. It is important to consult a best in class gastroenterologist regarding ANY and ALL symptoms or signs as it may a sign of a serious illness or condition. A thorough consultation and examination should ALWAYS be performed for an accurate diagnosis and treatment plan. Be sure to call a physician or call our office today and schedule a consultation.

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