From the Guidelines
SIBO (Small Intestinal Bacterial Overgrowth) is a condition characterized by an increased bacterial load in the small bowel, resulting in excessive fermentation and inflammation, and leading to adverse clinical symptoms such as malabsorption, abdominal discomfort, diarrhoea, constipation, flatulence, and bloating. This condition can complicate chronic pancreatitis in up to 92% of patients with pancreatic exocrine insufficiency (PEI) 1. The symptoms of SIBO may be confused with those of other conditions, and it is more likely to occur in individuals with a prior surgical history and heavy smokers.
Causes and Risk Factors
The exact causes of SIBO are not fully understood, but it is thought to be related to microbial imbalance (dysbiosis) in the large bowel, which may occur even without overgrowth into the small bowel 1. Studies have shown that decreased levels of Bifidobacteria and Lactobacilli, which are considered health-enhancing, may be clinically relevant in chronic pancreatitis patients 1.
Treatment and Management
Treatment for SIBO may require several courses of antibiotics, such as rifaximin, metronidazole, neomycin, or ciprofloxacin, depending on the type of bacterial overgrowth 1. Rifaximin is often the first choice if it is on the local drug formulary. A low FODMAP diet may help manage symptoms by reducing fermentable carbohydrates that feed bacteria. Prokinetic medications like low-dose erythromycin or prucalopride might be used to prevent recurrence by improving intestinal motility.
Key Considerations
It is essential to address the underlying cause of SIBO for long-term management, as it can recur after treatment. Bacterial overgrowth can result in cachexia without necessarily causing diarrhea, so antibiotics may be needed even in the absence of diarrhea 1. The risk of resistant organisms, including Clostridioides difficile, should also be considered when using antibiotics.
From the Research
Definition and Characteristics of SIBO
- Small intestinal bacterial overgrowth (SIBO) is a disorder characterized by the excessive growth of bacteria in the small intestine 2, 3, 4, 5, 6.
- This bacterial overgrowth disrupts the bacterial balance and can lead to abdominal pain, weight loss, and gastrointestinal symptoms, including bloating, diarrhea, and malabsorption 2, 3, 4, 5, 6.
Diagnosis of SIBO
- There are two main methods for diagnosing SIBO: breath tests and bacterial culture 2.
- The most commonly used method is a breath test, which enables the division of SIBO into the following three types: hydrogen-dominant (H-SIBO), methane-dominant (CH4-SIBO), and hydrogen/methane-dominant (H/CH4-SIBO) 2.
- Other diagnostic methods include glucose breath test, lactulose breath test, small intestinal aspiration and culture 3, 4.
Treatment and Management of SIBO
- Treatment of SIBO remains empirical; generally, broad spectrum antibiotics are recommended for 2 weeks (amoxicillin, rifaximin, ciprofloxacin, etc.) 3, 4.
- Clinical studies have shown that the efficacy of SIBO therapy can be increased by combining antibiotics with probiotics, especially in vulnerable patients such as children and pregnant women 2.
- Dietary modifications, such as low FODMAP diets, and probiotics can complement antibiotic therapy 4, 5, 6.
- Long-term follow-up is essential due to the recurrence rate, which is common in SIBO patients 4.