 The endpoint is bacteriological exam and the laboratory is blinded to the therapy status. Weekly urinary cultures are drawn and a sonication culture of the catheter tip is performed to detect and characterize the biofilm. A colonization rate of 95 is anticipated in the control arm. Therefore a 50 reduction in colonization can be detected with 54 patients, a 90 reduction in colonization can be detected with 20 patients with a power of 0.9. 