Small intestinal bacterial overgrowth

Introduction The blind sputum syndrome (enteric bacterial overgrowth syndrome (EBOS), mainly due to small intestinal stagnation, bacteria in the small intestine overgrowth and cause malabsorption, also known as intestinal collapse syndrome, intestinal infection syndrome or blind sputum syndrome . Under normal circumstances, the stomach and upper small intestine contain only a small amount of bacteria, because gastric acid and small intestine advancement can inhibit and eliminate bacteria. Any cause of hypoacidity or slowing or disruption of bowel movements can lead to excessive bacterial growth in the small intestine.

Cause

(1) Causes of the disease

Under normal circumstances, the stomach and upper small intestine contain only a small amount of bacteria, because gastric acid and small intestine advancement can inhibit and eliminate bacteria. Any cause of hypoacidity or slowing or disruption of bowel movements can lead to excessive bacterial growth in the small intestine.

Bacterial hyperplasia in the stomach

Low acid or no acid, gastric mucosal atrophy, postoperative gastric movement or abnormal anatomy (such as residual stomach after partial gastrectomy) have almost no gastric fundus glandular cells and no acid. In addition, Sachs studies have demonstrated that omeprazole inhibits H-K-ATPase in parietal cells and inactivates them. The binding of this proton pump inhibitor to the enzyme is irreversible, until the new enzyme in the cell is synthesized and transported to the apical membrane, and the enzyme activity is restored. This update process takes 48 hours, so taking 1 omeprazole can continue. 48h low acid.

2. Small intestinal deposition

(1) Anatomical reasons: input sputum of Billroth II surgery or gastrectomy, duodenal jejunal diverticulum, blind sputum caused by surgery, recurrent sputum surgery, intestinal stenosis, adhesions, inflammation and lymphoma obstruction.

(2) intestinal dyskinesia: scleroderma, idiopathic small intestine pseudo-obstruction, transitional complex motor absence or disorder, diabetic autonomic neuropathy.

(3) Abnormal intestinal passage: gastric-colon or jejunum-colon fistula, ileocecal valve resection.

3. Other chronic pancreatitis, immunodeficiency syndrome.

(two) pathogenesis

Overgrowth of intestinal bacteria can directly or indirectly affect the structure and function of the intestine, causing malabsorption. When the intestinal bacteria grows excessively, the bacteria can compete with the host for vitamin B12 in the diet. Although internal factors can inhibit the competition of vitamin B12 by aerobic bacteria, their rate of vitamin B12 intake is slowed down, but intestinal deposition can provide time for their intake. In addition, the intrinsic factor does not inhibit the uptake of vitamin B12 by Bacteroides, which, although it synthesizes vitamin B12, is firmly bound to the bacteria and cannot be used by the host. Therefore, vitamin B12 deficiency can occur and cannot be corrected by oral internal factors. However, since folic acid synthesized by the enterobacteria can be released into the intestinal lumen and can be utilized by the host, folic acid deficiency does not occur.

Overgrowth of small intestinal bacteria can interfere with the metabolism of bile salts, and the combined bile salts are decomposed into free bile salts, which are rapidly reabsorbed by the small intestine. Combined with the reduction of bile salts, the micelles are not easily formed, and fat absorption is poor, leading to diarrhea. In addition, when the free bile acid in the intestinal lumen reaches a certain concentration, it can also damage the submicrostructure of the epithelial cells and affect the absorption of sugar and protein.

Abnormal xylose tolerance test in patients with blind sputum syndrome may be caused by bacterial decomposition and utilization of xylose. Using 14C xylose to feed blind cockroaches, it can be measured that the urinary xylose content in the animal is decreased, and the 14CO2 content in the exhalation is increased. Clinically, according to this principle, the 14C xylose breath test is used for diagnosis. Intestinal bacterial overgrowth, common protein loss, increased nitrogen content in patients' feces and urine. Hypoproteinemia is caused by intestinal bacteria affecting the absorption of amino acids and protein-losing enteropathy.

an examination

Related inspection

Abdominal vascular ultrasound

Clinical manifestations vary greatly depending on the cause, and generally include symptoms of both malabsorption and primary disease. Lighter with mild diarrhea, mild anemia and weight loss. In severe cases, there are often watery diarrhea, steatorrhea, bloating, anemia, and weight loss. Severe fat malabsorption may occur with rickets, night blindness or even low calcium convulsions. Vitamin K deficiency can cause skin mucosal bleeding.

Anemia is mostly due to vitamin B12 deficiency, is a large cell anemia, sometimes caused by ulceration in the intestinal fistula, can cause small cell anemia or mixed anemia due to blood loss. Hypoproteinemia is common and dystrophic edema can occur.

Primary diseases such as surgical blind or small intestine stenosis, abdominal discomfort, bloating, diarrhea accompanied by umbilical hernia and anemia before diarrhea. Between blind formation and excessive bacterial growth, there is usually a longer interval, which is as short as several months and as long as several years. Sometimes the primary disease even masks the symptoms of bacterial overgrowth. Intestinal stenosis or fistula caused by small bowel Crohn's disease, intestinal movement caused by scleroderma or pseudo-intestinal obstruction is weakened. Some malabsorption caused by primary disease and malabsorption caused by bacterial overgrowth are difficult to identify, such as Crohn's disease, radiation enteritis, short bowel syndrome, lymphoma and so on. The jejunal diverticulum is more common in the elderly, and there are many intervals between the diverticulum and the bacterial overgrowth. It is often asymptomatic at first, and steatorrhea and anemia appear later.

Diagnosis depends mainly on small intestine content culture or breath test. Any slow-onset diarrhea, steatorrhea, weight loss, large cell anemia, especially in the elderly or patients with a history of abdominal surgery should consider intestinal bacterial overgrowth in the differential diagnosis. X-ray gastrointestinal angiography showed anatomical or functional abnormalities such as diverticulum, blind sputum, and fistula. Fibrocolonoscopy and biopsy can help with the diagnosis of the cause.

Differential diagnosis

1. A dysbacteriosis caused by antibiotics.

2. Gastrin (gastrin) deficiency after gastric antrum resection.

3. Intra-factor deficiency after subtotal or total gastrectomy.

4. Short bowel syndrome.

5. Primary intestinal malabsorption syndrome.

Any slow-onset diarrhea, steatorrhea, weight loss, large cell anemia, especially in the elderly or patients with a history of abdominal surgery should consider intestinal bacterial overgrowth in the differential diagnosis.

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