Mouse models of short- and long-term foreign body in the urinary bladder: analogies to the bladder segment of urinary catheters.

Catheter-associated bacteriuria is the most common infection occurring in hospitals, where urethral catheters are generally in place for a few days, and in nursing homes, where catheters may be in place for months or years. We developed murine models with intrabladder urinary catheters for studying complications of bacteriuria in short- and long-term catheterization. In the short-term model, a catheter segment was inserted transurethrally and lay free within the bladder lumen. Half of the animals expelled segments during a 2-to-7-day period, durations similar to catheterizations in hospitalized patients. For studies of long-term catheter use, the catheter segment was secured within the bladder by a single suture for up to 12 months. Antibiotics administered for 7 days after catheter placement and housing mice in cages with wire screen floors reduced spontaneous bacteriuria to an acceptably low incidence rate of only 7%. Proteus mirabilis bacteriuria of high concentration provoked the same complications that are common in patients with long-term catheters: acute pyelonephritis, chronic renal inflammation, and struvite stone formation. These models allow inoculation of the bacteria of interest and are suitable for studies of short- and long-term foreign body-associated bacteriuria and its complications.