Fig 3. The effect of p-HPA supplementation on competitive co-culture of C. difficile with E. coli and detection of p-cresol production.

a) A comparison of the percentage survival of C. difficile strain 630Δerm and E. coli in competitive co-culture for 24 hours, performed in 0.1%, 0.2% and 0.3% p-HPA. Statistical difference in percentage survival was calculated using regression analysis taking strain and media into consideration ***p<0.001. b) HPLC quantification of p-cresol production in competitive co-culture of C. difficile strain 630Δerm with E. coli in media supplemented with 0.1%, 0.2% and 0.3% p-HPA. Statistical difference in p-cresol production was calculated using a two tailed t-test with Welch’s correction, comparing individual p-cresol concentrations to the level produced in 0.1% p-HPA ***p<0.001.