Transmission of infection

Use of a closed system to collect urine dramatically decreases the incidence of bacteriuria; however, even with a closed system, bacteriuria will occur in almost all patients by 30 days. The duration of catheterization poses the greatest risk of bacteriuria. It has been estimated that for every day that a urinary catheter is in place the risk of infection increases by 3-10%.39 The majority of urinary tract infections are caused by the patients own endogenous intestinal flora, which migrates across the perineum and colonizes the periurethral area and enters the bladder during insertion of the catheter or by migration along the catheter lumen. The urethral catheter acts as a haven for colonizing bacteria, which are retained in a biofilm on the catheter surface. Furthermore, colonization of the catheter by urease-producing organisms may result in crystallization and blockage of the lumen.