An animal model for chronic infection of the unobstructed urinary tract.

Chronic cystitis due to Escherichia coli is frequently associated with anatomical or functional abnormalities of the lower urinary tract, but there is no satisfactory animal model available to help resolve biological and management problems. We have induced chronic infection of the unobstructed urinary tract in the rat by implanting a small polyurethane sponge into the dome of the bladder, 14 days before bacterial challenge. This manipulation provides a focus of infected urine and leads to the establishment of a chronic cystitis. Both the predisposing factor and the pathological details mimic important features of the disease in man.