Consistent with the in vitro competition data, the mtlD mutant was also less fit for colonizing the UT (median CIs, bladder, 3.8; catheter implant, 3.3; and kidneys, 3.5); kidney infection was detected in 75% (6/8) of mice coinfected with WT and mtlD (Fig. 4E). This evidence concerns the gene BMP1 and pyelonephritis.