Urinary tract infections (UTIs) are a common and clinically important outcome of the use of urinary catheters. Urinary catheters may be (1) short-term indwelling urethral catheters, (2) long-term indwelling urethral catheters, or (3) intermittent catheterization.

A patient has a short-term indwelling catheter when the duration of catheterization is less than 30 days and a long-term indwelling catheter when the catheter remains in situ more than 30 days. Considerations for indwelling suprapubic catheters are similar to those for indwelling urethral catheters. Different types of catheterization are indicated in different populations and have different risks for the occurrence of infection (Table 106.1).

PATHOGENESIS

Acquisition of urinary infection with catheter use is virtually always through ascending infection (Table 106.2). For indwelling urethral catheters, bacteria usually ascend into the bladder on the mucous sheath on the external surface of the catheter, up the drainage tubing in the urine column, or with bacterial biofilm on the inner surface of the tubing. Organisms colonizing the periurethral area ascending on the external surface of the catheter are a more common source of bacteriuria for women, and organisms gaining access through the tubing occurs more often in men. Disruption of the closed drainage system from the bladder to the drainage bag also may introduce bacteria, and there is a high incidence of urinary infection within 24 hours following such a break in the system. Bacteria introduced at the time of catheterization account for less than 5% of infections.