A–D, Mice were infected with 107 UTI89 KanR or mock-infected with PBS and followed for 4 wpi by longitudinal urinalysis in two independent experiments. All mice were treated with antibiotics at 4 wpi and sacrificed 4 weeks after initiation of antibiotic therapy. Paraffin-embedded, fixed bladder sections were stained with hematoxylin & eosin and examined by light microscopy. Representative images of mice that A, were mock-infected, B, had resolved bacteriuria, or C, had persistent bacteriuria are shown; bars approximate 50 µm in length. Statistics are the results of the Mann-Whitney U test: **, P<0.01, and ***, P<0.001. D, Bladders were weighed at sacrifice; horizontal bars indicate median values. E, Experimental time line for panel F: mice were followed by longitudinal urinalysis (each urine collection is indicated by small arrow) for the entire experiment to identify persistently bacteriuric mice prior to antibiotic therapy and after re-infection, and to confirm clearance of bacteriuria with antibiotic therapy. F–H, Combined time courses from two independent experiments each are displayed, charting the UTI89 SpcR urine bacterial titers during the 4 weeks after challenge infection, when antibiotic therapy was initiated at F, 28 days, G, 14 days, or G, 1 day after the initial infection. In all cases, mice were challenged 4 weeks after the initiation of antibiotic therapy. For panels F and G, mice are grouped by the outcome of urinalysis during the initial infection: Mock, mock-infected with PBS at week 0; Resolved Bacteriuria, infected with UTI89 KanR at week 0 and subsequently had at least one time point with <104 cfu/ml UTI89 KanR; or Persistent Bacteriuria, infected with UTI89 KanR at week 0 and had >104 cfu/ml UTI89 KanR for each time point. For panel H, mice are grouped by serum KC value at 24 hpi with UPEC: Mock, mock-infected with PBS at week 0; Resolved Bacteriuria, infected with UTI89 KanR at week 0 and have serum KC in the lower 50% of values at 24 hpi; or Persistent Bacteriuria, infected with UTI89 KanR at week 0 and had serum KC in the upper 50% of values at 24 hpi. Solid lines connect the urine titers over time for each individual mouse. Horizontal dashed lines represent the cutoff for significant bacteriuria in free catch urines: 104 cfu/ml.