Two mechanisms of adaptation to UTI conditions were observed in animal models: Labat et al. showed that a mutator strain could quickly evolve to avoid clearance and establish chronic infections (24), and Cooper et al. showed that deletion of MMR genes was selected for during a 48-h ascending UTI, presumably due to a higher switching rate of motility expression in MMR-deficient strains (25). Here, MRC1 is linked to bacterial urinary tract infection.