Empirical therapy for uncomplicated urinary tract infections in an era of increasing antimicrobial resistance: A decision and cost analysis

Infectious Diseases Society of America guidelines state that uncomplicated urinary tract infections (UTIs) should be treated empirically with trimetho prim-sulfamethoxazole (TMP-SMZ), unless the community resistance among urop athogens exceeds 10%-20%, in which case a fluoroquinolone (FQ) should be us ed. However, the data to support this threshold are limited. We performed a cost-minimization and sensitivity analysis to determine what level of TMP- SMZ resistance in a community should trigger FQ use. The mean cost of empir ical treatment with TMP-SMZ was US$92 when the proportion of resistant Esch erichia coli was 0%, $106 when it was 20%, and $120 when it was 40%. The me an cost of empirical FQ treatment was $107 at current levels of FQ resistan ce. When >22% of E. coli in a community are TMP-SMZ-resistant, empirical FQ therapy becomes less costly than TMP-SMZ therapy. Treatment guidelines for empirical treatment of UTIs may need modification, and the threshold trigg er for empirical FQ use should be raised to >20% TMP-SMZ resistance.