NR1H4 and clostridium difficile infection: FXR has differential activation depending on the bile acid it encounters in the order of CDCA>CA>LCA>DCA.104,106 Both murine and human FXR are activated by MCBAs, again with varying responses to each bile acid, the highest activation is with CDCA conjugates.63 Increased FXR signaling is associated with successful FMT, though FXR signaling does not appear to be significantly altered in patients with primary CDI.32,45