Optimising gut colonisation resistance against Clostridium difficile infection.

Clostridium difficile is the dominant cause of pseudomembranous colitis in nosocomial environments. C. difficile infection (CDI) generally affects elderly (≥65 years of age) hospital inpatients who have received broad-spectrum antimicrobial treatment. CDI has a 30 % risk of re-infection and a subsequent 60 % risk of relapse thereafter, leading to a high economic burden of over 7 billion pounds sterling and over 900,000 cases in the USA and Europe per annum. With the long-term consequences of faecal transplantation currently unknown, and limited spectrum of effective antibiotics, there is an urgent requirement for alternative means of preventing and treating CDI in high-risk individuals. Metagenomics has recently improved our understanding of the colonisation resistance barrier and how this could be optimised. pH, oxidation-reduction potentials and short-chain fatty acids have been suggested to inhibit C. difficile growth and toxin production in in vitro and in vivo studies. This review aims to pull together the evidence in support of a colonisation resistance barrier against CDI.