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Small Bowel Bacterial Overgrowth (SBBO)
Define SBBO?
SBBO usually is defined as an overgrowth of more than 105 CFU/mL of bacteria in
the proximal small bowel.
Discuss the mechanism of malabsorption in SBBO?
Malabsorption is due to the intraluminal effects of proliferating bacteria (degrading CHO and protein, using up B12) combined with damage to mucosal enterocytes. This damage lead to diminished disaccharidase activity; decreased transport of monosaccharides, amino acids and fatty acids; and protein losing enteropathy.
Fat malabsorption results from bacterial deconjugation of bile salts to form bile acids. These are readily absorbed in the jejunum leading to insufficient concentrations for normal fat absorption.
Discuss the disorders associated with bacterial overgrowth?
Growth of bacteria in small bowel is normally controlled by the ability of gastric acid to kill swallowed microorganisms and the cleansing effects of normal intestinal motility. Immunoglobulins in intestinal secretions and an intact IC valve are also important.
Some authorities think that SBBO is perhaps the most discernible cause of malabsorption in geriatric populations.
Discuss the clinical features of SBBO?
Abdominal discomfort, bloating, diarrhoea, flatulence, wt loss, weakness, neuropathy
Discuss the diagnosis of SBBO?
Patients should be tested and treated for SBBO in the presence of symptoms and a known predisposition to SBBO even in the absence of malabsorption.
In these breath tests, the diagnosis of SBBO is established when the exhaled breath H2 level increases by more than 10 parts per million greater than baseline on 2 consecutive samplings or if the fasting breath hydrogen level exceeds 20 parts per million. In patients with SIBO and an intact intestine, a peak occurs within 1 hour and is less prominent than the normal colonic peak.
The specificity is compromised when hydrogen is produced by colonic bacteria, especially when transit times are accelerated by the osmotic load of the substrate dose. Further upto 18% of persons are H2 non excretors. The test will false negative in these pts as H2 is metabolised by bacteria to methane.
Discuss the treatment of SBBO?
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