Prophylactic methenamine hippurate or nitrofurantoin in patients with an indwelling urinary catheter.

One hundred and twenty three elderly patients without urinary tract infection who required an indwelling urinary catheter because of cerebrovascular disease were divided into three groups. One was given methenamine hippurate (MH), one nitrofurantoin (NF), while a control group received no prophylactic urinary tract disinfectant. Catheter complications, symptomatic urinary tract infections and the clinical course were recorded. At regular intervals bacteria were cultured from the urine, tests were made for antibody-coated bacteria (ACB) and routine laboratory investigations were performed. NF significantly delayed the appearance of ACB; however, it did not prevent their appearance if a catheter was used for more than two months, by which time ACB were present in most patients irrespective of treatment. MH had less effect on the bacteriological findings, although it significantly decreased the need for antibiotic courses given for treatment of symptomatic urinary tract infections. In both MH- and NF-groups there were fewer patients with mechanical catheter complications. Forty seven patients died, generally due to cerebrovascular disease, and 22 autopsies were performed. Gross inflammatory changes in the urinary tract were commonly found at autopsy in all groups if a catheter had been used for more than two weeks. A positive test for ACB considerably increased the probability of inflammatory changes in the kidneys, but because of the frequency of such changes after prolonged use of an indwelling catheter, the test does not seem to offer much advantage as a guideline for therapy. Prophylactic urinary tract disinfectants may not be warranted in all patients with an indwelling catheter. If, however, recurrent clinical complications such as clogging of the catheter or symptomatic infection occur, continuous use of a urinary tract disinfectant is indicated. MH is preferred because it has fewer side effects than NF.