To determine if yeaR influenced IBC development and UTI pathogenesis, separately from its effects on type 1 piliation, we inoculated mice transurethrally with each of the UTI89, ΔyeaR, LIR ΔyeaR, and LIR UTI89 strains and examined IBC formation and CFU at 6 hpi. This evidence concerns the gene CD300C and bacterial urinary tract infection.