fig2

Figure 2. Differential effects of dietary metabolites on pathogens; metabolites from fibre degradation by commensals have differential effects on the success of an invading pathogen. Acetate promotes the growth of Enterohemorrhagic E. coli (EHEC), whereas butyrate and propionate repress growth. Conversely, acetate represses Salmonella growth, whereas butyrate and propionate promote growth. Colonisation of Clostridioides difficile is increased by the cholesterol metabolites, primary bile acids. The commensal Clostridium scindens can limit the availability of primary bile acids by converting these to secondary bile acids, thus increasing colonisation resistance to C. difficile. SCFAs: Short-chain fatty acids.