Excess bacterial growth in the small intestine

Excess bacterial growth in the small intestine may be a consequence of anatomical changes in the intestine or disorders of the motility of the gastrointestinal tract, as well as a lack of gastric secretion. These disorders can lead to a deficiency of vitamins, malabsorption of fats and malnutrition. The diagnosis is established by a respiratory test with ¹⁴ Xylose. Treatment of excess bacterial growth in the small intestine consists in the oral administration of antibiotics.

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What causes excessive bacterial growth in the small intestine?

Normally, the proximal small intestine contains less than 10 bacteria / ml, mainly Gram-positive aerobic bacteria. This low bacterial index is maintained by normal peristalsis, adequate gastric secretion of acid, mucus, secretory IgA and functioning ileocecal sphincter.

Usually, excessive bacterial growth develops in the case of anatomical changes that cause stasis of intestinal contents. These changes include small intestine diverticulosis, blind intestinal loops after surgery, post-gastrectomy status (especially in the resulting loop after the Billroth II surgery), constriction or partial obstruction. Also, bacterial growth disorders of intestinal motility associated with diabetic neuropathy, systemic scleroderma, amyloidosis and idiopathic intestinal pseudo-obstruction may contribute to bacterial growth. Achlorhydria and idiopathic changes in intestinal motility can cause excessive bacterial growth in the elderly.

Excess bacteria consumes the nutrients, including vitamin B ₁₂ and carbohydrates, leading to a deficiency of vitamin deficiency in energy and ₁₂. However, since bacteria synthesize folate, folate deficiency is rare. Bacteria deconjugate the bile salts, causing deficiency of micelle formation and subsequent malabsorption of fat. Excessive bacterial growth in severe cases damages the intestinal mucosa.

Symptoms of excessive bacterial growth in the small intestine

In many patients, the disease of excessive bacterial growth in the small intestine is asymptomatic and manifests itself only by weight loss or malnutrition. Sometimes there may be severe diarrhea or steatorrhea.

Diagnosis of excess bacterial growth in the small intestine

Some clinicians evaluate the effectiveness of empirical antibacterial therapy as a diagnostic test. However, since excess bacterial growth may resemble other malabsorption disorders (eg, Crohn's disease), and the side effects of antibiotic therapy may worsen the course of the disease, the cause should be clearly establishedviolations.

Standard for diagnosis - quantification of microflora in intestinal contents obtained by aspiration (the number of bacteria> 10 / ml). This method, however, requires endoscopy. Respiratory tests are not invasive and easy to perform. The respiratory test with ¹⁴ Xylose is the most sensitive and specific. In addition, it is necessary to perform a survey of the upper digestive tract, including the small intestine, in order to identify predisposing anatomical disorders.

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Treatment of excess bacterial growth in the small intestine

Treatment of excess bacterial growth in the small intestine is in the oral administration of antibiotics for 10-14 days. Empirical regimens include tetracycline 250 mg 4 times a day, amoxicillin / clavulanic acid 250-500 mg 3 times a day, cephalexin 250 mg 4 times a day, trimethoprim sulfamethoxalone 160/800 mg 2 times a day and metronidazole 250-500 mg 3 or 4 times a day. The administration of antibiotics should be based on the results of bacterial inoculation and sensitivity. Causes and disorders in nutrition should be eliminated (eg, vitamin B ₁₂ ).