Effect of Fiber Source on Short-Chain Fatty Acid Production and on the Growth and Toxin Production by Clostridium difficile

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Abstract
May T. Mackie RI. Fahey GC Jr, Cremin JC. Garleb KA. Effect of fiber source on short-chain fatty acid production and on the growth and toxin production by Clostridium difficile. Scand J Gastroenterol 1994;19:916-922. Background: Fermentable fiber promotes the growth of resident gut microbes, which modify the environment of the gastrointestinal tract and thus prevent colonization by Clostridium difficile. Methods: An in vitro system with pigs as fecal inoculum donors was used to estimate fiber fermentability and changes in intestinal microbicta. Results: Acetate and propionate production (μmol/mg substrate fermented/day) was greatest for gum arabic (1013.4 and 704.1, respectively): butyrate production was greatest for xylo-oligosaccharide (345.6). Growth of total anaerobes and Clostridia was greatest for gum arabic (21.2 and 16.2 × 108 counts/ml, respectively) and xylo-oligosaccharides (21.0 and 19.6 × 108 respectively); growth of acidogenic bacteria was greatest with fructo-oligosaccharide (6.7 × 108 counts/ ml). No culturablc counts of C. difficile were obtained, nor was toxin A detected. Conclusions: Fermentable fibers support the growth of indigenous intestinal bacteria, particularly acidogenic bacteria, and yield large amounts of short-chain fatty acids with decreased gut pH. These factors contribute to the prevention of growth and toxin elaboration by C. difficile.