False positive D-xylose test seen in-
Blind loop syndrome The normal duodenum and jejunum contain fewer than 104/mL organisms, which are usually derived from saliva. The count of coliform organisms never exceeds 103/mL. In bacterial overgrowth, there may be 108-1010/mL organisms, most of which are normally found only in the colon. Disorders that impair the normal physiological mechanisms controlling bacterial proliferation in the intestine predispose to bacterial overgrowth . The most impoant are loss of gastric acidity, impaired intestinal motility and structural abnormalities that allow colonic bacteria to gain access to the small intestine or provide a secluded haven from the peristaltic stream. Pathophysiology Bacterial overgrowth can occur in patients with small bowel diveiculi. Another cause is diabetic autonomic neuropathy , which reduces small bowel motility and affects enterocyte secretion. In systemic sclerosis, bacterial overgrowth arises because the circular and longitudinal layers of the intestinal muscle are fibrosed and motility is abnormal. In idiopathic hypogammaglobulinaemia , bacterial overgrowth occurs because the IgA and IgM levels in serum and jejunal secretions are reduced. Chronic diarrhoea and malabsorption occur because of bacterial overgrowth and recurrent gastrointestinal infections (paicularly giardiasis, ). Clinical features The patient presents with watery diarrhoea and/or steatorrhoea, and with anaemia due to B12 deficiency. These arise because of deconjugation of bile acids, which impairs micelle formation, an because of bacterial utilisation of vitamin B12. There may also be symptoms from the underlying intestinal cause. Investigations The diagnosis of blind loops or fistulae can often be made by barium small bowel meal and follow-through or small bowel MRI enterography. Endoscopic duodenal biopsies are useful in excluding coeliac disease. Jejunal contents for bacteriological examination can also be aspirated at endoscopy but laboratory analysis requires anaerobic and aerobic culture techniques. Bacterial overgrowth can also be diagnosed non-invasively using hydrogen breath tests, although they lack sensitivity. These simple, non-radioactive tests involve serial measurement of breath samples for hydrogen after oral ingestion of 50 g of glucose or lactulose. If bacteria are present within the small bowel, they rapidly metabolise the glucose, causing an early rise in exhaled hydrogen, in advance of that normally resulting from metabolism by colonic flora. Biochemical analysis may reveal low serum levels of vitamin B12, with normal or elevated folate levels because the bacteria produce folic acid. Hypogammaglobulinaemia can be diagnosed by measurement of serum immunoglobulins and by intestinal biopsy, which shows reduced or absent plasma cells and nodular lymphoid hyperplasia. Ref Davidson edition23rd pg 808
Blind loop syndrome
Ascites
Renal failure
Antibiotic therapy
G.I.T