Sex, drugs, bugs, and age: rational selection of empirical therapy for outpatient urinary tract infection in an era of extensive antimicrobial resistance

background: optimal empirical therapy of urinary tract infection requires accurate knowledge of local susceptibility patterns, which may vary with organism and patient characteristics. methods: among 9,798 consecutive, non-duplicate, community-source urine isolates from ambulatory patients > 13 years old, from clinical laboratory and an academic medical center in curitiba, brazil (may 1st to december 1st, 2009), susceptibility data for ampicillin, nitrofurantoin, trimethoprim-sulfamethoxazole, gentamicin, fluoroquinolones, and ceftriaxone/cefotaxime were compared with organism and patient gender and age. results: the female-to-male ratio decreased with age, from 28.1 (among 20-29 year-olds) to 3.3 (among > 80 year-olds). overall, susceptibility prevalence varied widely by drug class, from unacceptably low levels (53.5% and 61.1%: ampicillin and trimethoprimsulfamethoxazole) to acceptable but suboptimal levels (81.2% to 91.7%: fluoroquinolones, ceftriaxone, nitrofurantoin, and gentamicin). e. coli isolates exhibited higher susceptibility rates than other isolates, from 3-4% higher (fluoroquinolones, gentamicin) to > 30% (nitrofurantoin, ceftriaxone). males exhibited lower susceptibility rates than females. within each gender, susceptibility declined with increasing age. for females, only nitrofurantoin and gentamicin were suitable for empirical therapy (> 80% susceptibility) across all age cohorts; fluoroquinolones were suitable only through age 60, and ceftriaxone only through age 80. for males, only gentamicin yielded > 80% susceptibility in any age cohort. conclusion: few suitable empirical treatment options for community-source urinary tract infection were identified for women aged over 60 years or males of any age. empirical therapy recommendations must consider the patient's demographic characteristics. site-specific, age and gender-stratified susceptibility surveillance involving all uropathogens is needed.