To determine whether some proteins identified by 2D-DIGE are required for UPEC fitness during UTI, CFT073 mutants were constructed in the genes: talA, xylA, tpiA, serA, speB, uxuA, nanA, argG, araF, dppA, and oppA. For these studies, an experimental competition between each mutant strain and wild-type parental CFT073 was performed. The gene discussed is PHGDH; the disease is bacterial urinary tract infection.