Small Intestinal Bacterial Overgrowth
Patient Guideline Summary
Publication Date: February 1, 2020
Last Updated: March 2, 2023
Objective
Objective
This patient summary means to summarize key recommendations from the American College of Gastroenterology (ACG) for the diagnosis and treatment of small intestinal bacterial overgrowth. This patient summary is limited to adults 18 years of age and older and should not be used as a reference for children.
Overview
Overview
- Small intestinal bacterial overgrowth is a clinical syndrome of gastrointestinal (GI) symptoms caused by the presence of large numbers of bacteria within the small intestine. This bacterial overgrowth results in GI signs and/or symptoms. For example, the pathologic fermentation of food could lead to the production of excess gas and bloating.
- We will use the abbreviation SIBO throughout this summary to refer to small intestinal bacterial overgrowth.
- Abdominal pain, bloating, gas, distension, flatulence (passing wind), and diarrhea are the most common symptoms described in patients with SIBO. The most common of all of them is bloating.
- The causes of SIBO vary and may need to be known to best prevent a recurrence.
Diagnosis of SIBO
Diagnosis of SIBO
- Your doctor may use breath testing (a measurement of exhaled hydrogen gas in the breath after taking a fixed quantity of a carbohydrate such as glucose [75 g] or lactulose [10 g]) to confirm the diagnosis of SIBO if:
- you have irritable bowel syndrome (IBS), because some patients with IBS have SIBO.
- your symptoms suggest a motility disorder.
- Motility disorders are caused by nerve or muscle problems (for example: scleroderma and diabetes) or by medications such as opioids, antidiarrheals, or anticholinergics, that slow the bowels and encourage bacterial overgrowth.
- you are symptomatic (abdominal pain, gas, bloating, and/or diarrhea) from previous abdominal surgery.
- ACG does not suggest the use of breath testing for the diagnosis of SIBO if you don’t have symptoms and are using proton-pump inhibitors (PPIs) (drugs used for acid indigestion).
- If you have constipation, your doctor may test for methane using glucose or lactulose breath tests to diagnose an overgrowth of methane-producing organisms called intestinal methanogen overgrowth (IMO).
- The presence of excessive methane on breath testing does not indicate SIBO since methanogens are not bacteria (they are other organisms called archaea). So, we use the term IMO.
Treatment of SIBO
Treatment of SIBO
- If you have symptoms of SIBO, your doctor may prescribe antibiotics to eliminate overgrowth and relieve symptoms.
The following table lists the suggested antibiotics for treatment of SIBO
Antibiotic | Dose |
---|---|
Rifaximin | 550 mg t.i.d. |
Amoxicillin-clavulanic acid | 875 mg b.i.d. |
Ciprofloxacin | 500 mg b.i.d. |
Doxycycline | 100 mg q.d. to b.i.d. |
Metronidazole | 250 mg t.i.d. |
Neomycin | 500 mg b.i.d. |
Norfloxacin | 400 mg q.d. |
Tetracycline | 250 mg q.i.d. |
Trimethoprim-sulfamethoxazole | 160 mg/800 mg b.i.d. |
q.d.: one time a day
b.i.d.: two times a day
t.i.d.: three times a day
q.i.d.: four times a day
b.i.d.: two times a day
t.i.d.: three times a day
q.i.d.: four times a day
- There is a lack of consistent data for the use of specific probiotics (good bacteria) in the treatment of SIBO.
- There is no basis for the use of fecal microbiota transplant in the treatment of SIBO.
- A focus on prevention of SIBO is important to avoid the need for repeated use of antibiotics. Treatment of the underlying cause represents the primary method of prevention.
Abbreviations
- ACG: American College Of Gastroenterology
- GI: Gastrointestinal
- IBS: Irritable Bowel Syndrome
- IMO: Intestinal Methanogen Overgrowth
- PPIs: Proton-pump Inhibitors
- SIBO: Small Intestinal Bacterial Overgrowth
- b.i.d.: Twice A Day
- q.d.: Once A Day
- q.i.d.: Four Times A Day
- t.i.d.: Three Times A Day
Source Citation
Pimentel, Mark MD, FRCP(C), FACG; Saad, Richard J. MD, FACG; Long, Millie D. MD, MPH, FACG (GRADE Methodologist); Rao, Satish S. C. MD, PhD, FRCP, FACG. ACG Clinical Guideline, The American Journal of Gastroenterology: February 2020 - Volume 115 - Issue 2 - p 165-178 doi: 10.14309/ajg.0000000000000501
Disclaimer
The information in this patient summary should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.