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

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.

Key Words:

• Clostridium difficile
• colonization resistance
• fermentation
• fiber
• short-chain fatty acids