Understanding and Managing Small Intestinal Bacterial Overgrowth (SIBO) - Dr Bhuvan Shetty

Published On 2024-03-20 09:35 GMT | Update On 2024-03-20 09:35 GMT

Small intestinal bacterial overgrowth (SIBO) is a well-recognized cause of maldigestion and malabsorption. It is defined as “a disease in which the small bowel is abnormally colonized by an increased number and abnormal types of microorganisms".

This imbalance in the number of bacteria can disrupt the normal digestive process, leading to various symptoms. Early recognition of the symptom is crucial for effective treatment.

The human gut is inhabited by 1014 bacterial cells, with approximately 500 to 1,000 different bacterial species identified to date.

Risk Factors

The prevalence of SIBO among the general population is not known, but in most studies, SIBO has been detected anywhere from 0 to 20% of healthy controls.

1) Digestive Disorders

Conditions like irritable bowel syndrome (IBS), Crohn's disease, celiac disease, and gastroparesis can disrupt the normal balance of bacteria in the small intestine.

2) Anatomical Abnormalities

Structural issues in the gastrointestinal tract, such as strictures, fistulas, or surgical alterations, can slow down the movement of food and create an environment where bacteria can overgrow.

3) Medications

Certain medications, such as proton pump inhibitors (PPIs), antibiotics, narcotic pain relievers, and immune-suppressing drugs, can disrupt the normal balance of bacteria in the gut, predisposing to SIBO.

4) Low Stomach Acid

Reduced stomach acid levels, which can occur due to aging, stress, or the use of acid-suppressing medications, can allow bacteria to survive in the stomach and migrate to the small intestine.

5) Impaired Motility

Conditions that affect the normal movement of the digestive tract, such as diabetes, scleroderma, and intestinal pseudo-obstruction, can lead to bacterial overgrowth by slowing down the transit of food through the small intestine.

6) Dietary Factors

Diets high in carbohydrates, sugar, and refined foods can provide a favourable environment for bacteria to proliferate in the small intestine.

7) Immune System Dysfunction

Conditions that weaken the immune system, such as HIV/AIDS, autoimmune diseases, and chemotherapy, can impair thbody's's ability to control bacterial populations in the gut, increasing the risk of SIBO.

8) Age

SIBO is more common in older adults, possibly due to age-related changes in digestive function and immune response.

Symptoms

The symptoms of SIBO are nonspecific, and their frequency and severity likely reflect both the degree of bacterial overgrowth and the extent of mucosal inflammation.

1) Patients usually present with

2) Loss of appetite

3) Abdominal pain

4) Nausea

5) Bloating

6) An uncomfortable feeling of fullness after eating

7) Diarrhoea

8) Unintentional weight loss

9) Malnutrition

Clinical Manifestation

1) Weight Loss

2) Steatorrhea or Increased Excretion of fat with faeces due to reduced absorption of fat by intestine

3) Vitamin/mineral deficiency like fat-soluble vitamins (A, D, E, K), Vitamin B12, Iron

4) Hyperproteinaemia

Diagnosis

Multiple Tests are available for diagnosing SIBO.

Breath tests are simple, non-invasive, patient-friendly methods for diagnosing bacterial overgrowth. The glucose hydrogen breath test is commonly used to measure hydrogen levels in the breath. Elevated levels indicate Small intestinal bacterial overgrowth.

Treatment

Mainstay of treatment includes reducing symptoms and restoring normal bacterial microbiota in the intestine.

1) Antibiotics: It helps to eradicate bacterial overgrowth and repletion of any nutritional deficiencies.

2) Probiotics: It helps to restore healthy gut bacteria and help maintain healthy gut health

3) Lifestyle modification: A key principle in managing SIBO is identifying and treating any predisposing factors using a combination of dietary, lifestyle, medical, and surgical therapies. Lifestyle measures include avoiding sugar, reducing NSAID use, and smoking cessation.

In conclusion, SIBO remains a widely prevalent diagnosis but is often overlooked. Early recognition of the symptoms and treatment helps improve the quality of life.

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Dr Bhuvan Shetty

Dr Bhuvan Shetty MBBS, MD (General Medicine), DM (Gastroenterology) is a Consultant Gastroenterologist at Gleneagles Hospital, Bengaluru, with 14 years of experience in the field. Dr Bhuvan Shetty specialises in Digestive Health, Gut Health, Hepatology, and Gastroenterology.

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