The value of single-dose therapy to diagnose the site of urinary infection

Several single dose regimens have been shown to cure 90 percent of women with acute cystitis in whom infection is confined to the bladder. About 25 percent of women with acute cystitis and approximately one-half with asymptomatic infection have organisms originating from one or both upper urinary tracts. Effective single dose regimens such as trimethoprim-sulfamethoxazole, amoxicillin, and trimethoprim alone, cure between 40 and 60 percent of upper tract infections in women with renal involvement, who present with acute cystitis or with asymptomatic bacteriuria. Five studies have shown that single dose failure in women with acute cystitis or asymptomatic bacteriuria is a specific predictor of upper tract infection. It is also sensitive (60-80 percent) in predicting upper tract pathology. The evidence to date favours the hypothesis that failure of single dose cure following treatment with an effective single dose regimen in adult women who have asymptomatic bacteriuria or acute cystitis, identifies a subset of women who require further investigation of the urinary tract.