Effects of an enteric anaerobic bacterial culture

Fifty two strains of anaerobic bacteria isolated from the upper gut of patients with small intestinal bacterial overgrowth were screened for phospholipase activity. Bacteroides melaninogenicus spp intermedius had the greatest activity. The effects of culture supernatants of this organism and deoxycholate on intestinal calcium absorption and disaccharidase activity were studied using a rat closed loop model. The supernatant decreased the in vitro uptake of calcium by 15% (p<0-001). Deoxycholate reduced calcium uptake by 16% (p<0-001). Combined culture supernatant and deoxycholate reduced calcium uptake by 39% (p<0001) suggesting a potentiation of supernatant activity by deoxycholate. Culture supernatant and deoxycholate, both alone and combined, significantly reduced lactase, sucrase, and maltase activity. Electron microscopic evidence showed degeneration of microvilli, disruption of mitochondrial structure, and swelling of the endoplasmic reticulum after exposure ofthe intestinal loops to the supernatant or deoxycholate. Department of Clinical Medicine, Biochemistry and Microbiology, Trinity College and St James's Hospital, Dublin 8 K Walshe M J Healy A B J Speekenbrink C T Keane D G Weir R R O'Moore Correspondence to: Dr Rory R O'Moore, Department of Biochemistry, Central Pathology Laboratory, St James's Hospital, Dublin 8. Accepted for publication 11 September 1989 The pathogenesis of contaminated small bowel syndrome remains controversial. It is characterised clinically by malabsorption of fats, fat soluble vitamins, and vitamin B12.' Protein calorie malnutrition2 and carbohydrate malabsorption3 may also occur. The intestinal fat malabsorption in contaminated small bowel syndrome is usually attributed to bacterial deconjugation of bile salts leading to inadequate micelle formation.4 Several studies, however, have shown the presence of mucosal damage associated with contaminated small bowel syndrome.5'Various toxic products of bacterial metabolism have been suggested as aetiological