What is small intestinal bacterial overgrowth (SIBO)?

Small intestinal bacterial overgrowth (SIBO) is a condition where the small intestine develops a higher number of bacteria than the large intestine. Over time, an excessive number of bacteria can enter and multiply in the small intestine, leading to poor absorption of nutrients and even malnutrition.

SIBO is also commonly referred to as small bowel bacterial overgrowth.

Children’s Hospital of Philadelphia (CHOP) gastroenterologists are knowledgeable about all pediatric intestinal issues and have extensive experience successfully treating conditions such as SIBO.

What are the symptoms of SIBO?

Bacteria exist in your intestines normally. Too much or the wrong type of bacteria can cause problems with your digestive system.

Specific symptoms of SIBO include:

• Abdominal bloating
• Excessive gassiness (flatulence)
• Abdominal pain or discomfort
• Abdominal swelling caused by pressure (distention)
• Diarrhea
• Unintentional weight loss
• Nausea

These symptoms are not specific to SIBO. While a child presenting some or even most of these symptoms may have SIBO, it’s important to remember that many of these symptoms may also be seen with other GI conditions.

What does SIBO stool look like?

If your child has small intestinal bacterial overgrowth, their stool may seem different than normal. This is because SIBO can make it difficult for your child’s body to process fats, causing stool to be especially smelly or oily.  

Other possible changes that could indicate SIBO include stool that is:

• Soft, loose or watery 
• Thin 
• Hard and lumpy  

What causes SIBO?

At times, the bacteria naturally present in our bodies can increase in number, far beyond what is normal. This can impact a child’s digestive system.

Increased bacteria in the small intestine can be caused by many things, including:

• Low stomach acid
• Decreased GI tract movement (motility)
• Intestinal lining damage
• Intestine structural damage

These issues lead to bacteria remaining in the small intestine for a longer time, allowing them to multiply.

These causes can be present at birth (congenital) or develop because of other interventions, such as the overuse of certain medications.

It is rare to have small bowel bacterial overgrowth without an underlying cause or risk factor.

What are the risk factors of SIBO?

There are some conditions linked to an increased risk of developing SIBO.  

These conditions include: 

• Celiac disease
• Gastroparesis
• Small bowel dysmotility
• Short bowel syndrome
• Chronic pancreatitis
• Connective tissue disorders
• Inflammatory bowel disease (IBD)
• Irritable bowel syndrome
• Chronic intestinal pseudo-obstruction
• Certain medications
• Prior GI surgery

At CHOP, our doctors are experienced with SIBO and all associated conditions and are prepared to arrive at your child’s bedside with understanding, compassion and, most importantly, answers. 

Which foods trigger SIBO?

Certain foods are associated with a higher likelihood of developing small intestinal bacterial overgrowth in at risk populations. While these foods don’t cause SIBO, they can contribute to the overgrowth of bacteria. 

Foods that may trigger SIBO include:

• Sugars and sweeteners 
• Fruits and starchy vegetables 
• Dairy products 
• Grains  

Often avoiding these foods starves bad bacteria and can lead to decreased symptoms.  

How do you test and diagnose SIBO?

Diagnosing small intestinal bowel overgrowth includes obtaining a comprehensive medical, surgical and symptom history to identify risk factors and symptoms that may be suggestive of bacterial overgrowth. The physical exam will help your child’s physician evaluate nutritional status and for underlying disorders that have been linked to an increased risk for SIBO. 

Diagnostic screening testing may include imaging (CT, MRI, X-ray) of the abdomen and bowel to evaluate dilated loops of bowel and screen for any areas of narrowing of the bowel causing decreased motility through the intestines.  

Diagnostic testing for SIBO may also include: 

• Bacterial culture of the bowel 
• Hydrogen breath test  

Bacterial culture of the bowel 

The bacterial culture of the bowel is a direct method of testing using endoscopy to obtain samples from the small intestine. This test is not commonly used due to the procedure being invasive and requiring endoscopy to obtain a specimen. The results obtained are only indicative of the location where the specimen was obtained and can underestimate the total number of actual bacteria present in other areas of the small bowel. 

Hydrogen breath test

The most common test used to diagnose bacterial overgrowth is the hydrogen breath test. This test is a simple and non-invasive way to indirectly test bacterial overgrowth. During this test, your child will drink a substrate (glucose or lactulose) that will interact with the bacteria in the small bowel to produce byproducts that can be measured in the exhaled breath. Timed interval measures of the exhaled breaths are used to detect changes in hydrogen production and methane production which are indicative of bacterial overgrowth. Because it is an indirect measure of bacterial load, it is not a perfect test.   

How do you treat SIBO?

The goals of treatment for SIBO are to correct the predisposing or underlying cause of bacterial overgrowth, provide nutritional support, and treat the bacterial overgrowth.  

Treatment is aimed at identifying and correcting the underlying causes of bacterial overgrowth and may include diet management and medication management. In some instances, surgical management may be indicated to correct identified defects in the intestinal anatomy that can contribute to bacterial overgrowth.  

Dietary management is aimed at providing education to families about foods that do not contribute to producing excess gas and providing dietary guidance to maintain vitamin and nutritional needs. 

What are the recommended antibiotics for SIBO?

Antibiotics are prescribed for management of SIBO to reduce the bacterial overgrowth and treat the inflammation to the bowel lining caused by SIBO.

Some of the antibiotics commonly used include:

• Metronidazole (Flagyl^®) 
• Ciprofloxacin (Cipro^®) 
• Neomycin 
• Amoxicillin-Clavulanic Acid (Augmentin)
• Rifaximin (Xifaxan^®)

The specific antibiotic used is based on each individual patient’s history.

Duration of treatment with antibiotics may be short term (seven to 14 days), or a longer course may be prescribed. Antibiotics may also be cycled for use during a specified amount of time each month as ordered if the underlying risk factor for SIBO cannot be treated. 

How can I prevent SIBO from recurring?

Often, keeping SIBO from coming back means addressing the underlying condition that causes it. Those conditions, outlined above, can vary greatly in symptoms and treatments. They also vary in terms of what might keep SIBO from recurring.   

It is not uncommon for SIBO to return, even shortly after a round of antibiotics.  

Depending on the underlying cause of your SIBO, helpful steps for prevention may include: 

• Antibiotics (short term) 
• Surgery 
• Medication adjustment 
• Alcohol or diet adjustment 

Even if there is no underlying cause identified, diet adjustment is often an important part of SIBO prevention. Cutting down on carbohydrates can be a key first step. 

What is the long-term outlook for children with SIBO?

Children treated for short intestinal bacterial overgrowth see an improvement of symptoms and quality of life with treatment. Long-term outcomes are positive if underlying and predisposing conditions are identified and properly managed. 

What is the follow-up care for SIBO?

Follow-up care for small intestinal bacterial overgrowth may require ongoing management based on symptoms and the continued management of underlying causes leading to bacterial overgrowth. If there are no recurrent symptoms or a serious underlying disorder, follow-up care may not be needed. 

Why choose CHOP for SIBO care

We have extensive experience in the diagnosis and management of bacterial overgrowth secondary to a variety of underlying factors and conditions. CHOP excels in providing comprehensive care for every patient, including the medical, pharmaceutical and nutritional management of bacterial overgrowth and the underlying condition.