Antimicrobial Prophylaxis of Recurrent Urinary Tract Infections

Abstract

To study once-daily antimicrobial prophylaxis of urinary tract infections, one gave trimethoprim-sulfamethoxazole (40 mg/200 mg), trimethoprim (100 mg), nitrofurantoin macrocystals (100 mg) or placebo to 60 women for 6 mo. During prophylaxis, infections/patient year were comparable in the groups receiving trimethoprim (0.0), nitrofurantoin (0.14) or trimethoprim-sulfamethoxazole (0.15) and occurred less frequently than in patients receiving placebo (2.8; P < 0.001, placebo vs. each drug regimen). The effectiveness of prophylaxis was limited to the 6 mo. That antimicrobials were given, and infections were more likely to develop after prophylaxis in women who had 3 or more infections in the year before prophylaxis (P < 0.005). Women whose preprophylaxis infection was positive for antibody-coated bacteria were more likely to have same-strain relapse when infections recurred (P = 0.001). Emergence of trimethoprim-resistant Escherichia coli was rare, but non-E. coli infections occurred more often after prophylaxis (P < 0.05). Prophylaxis with these drugs is effective, well tolerated and did not produce emergence of resistant E. coli but may predispose to non-E. coli urinary tract infections after its discontinuation.