Forty-week-old SAMP1/YitFc mice with spontaneous CD-like ileitis and ileal fibrosis were used to determine the mechanisms of action of oral fidaxomicin treatment (Figure 6A).17,31 Consistent with our previous study,13 the 42-week-old SAMP1/YitFc mice had ileal mucosal injuries and fibrosis compared with the normal-appearing ileal structure in their control AKR mice (Figure 6B). This evidence concerns the gene TMEM201 and Crohn ileitis.