BackgroundAntimicrobial prescriptions are relatively common in urologic outpatients. Therefore, it is necessary to investigate the impact of antimicrobial stewardship program (ASP) interventions. MethodsIn urology outpatients, antimicrobial use density (AUD), antimicrobial agent costs, isolation of urinary tract infection (UTI)-causing organisms and their antimicrobial susceptibilities were compared between intervention by infection control team (ICT) era (pre-2014) and ASP era (post-2014) in 2739 patients with lower urinary tract symptoms, including neurogenic bladder patients with UTI or suspected UTI, from 2011 to 2020. ResultsIn the ASP, overall AUD (P<.001), cefotiam (CTM) (P=.0013), 2nd-generation cephalosporins (P=.026), cefdinir (CFDN) (P<.001), levofloxacin (LVFX) (P<.001), sitafloxacin (STFX) (P=.0016), and tosufloxacin (TFLX) (P=.0044) showed a significant decrease, but cefaclor (P=.019) showed a significant increase. Regarding antimicrobial agent costs, overall (P=.016), CTM (P=.021), 2nd-generation cephalosporins (P=.033), CFDN (P=.016), LVFX (P=.016), STFX (P=.033), and TFLX (P=.033) showed a significant decrease in the ASP. UTI-causing antimicrobial susceptibilities, CTM (P=.035), LVFX (P=.026) and sulfamethoxazole/trimethoprim (P=.048) in E. coli, and minocycline (P=.026) in K. pneumoniae showed a significant improve in the ASP. ConclusionASP contributed to decrease AUD and antimicrobial agent costs, and to improve antimicrobial susceptibilities of E. coli and K. pneumoniae to several antibiotics, compared to ICT. Further prospective studies are necessary for definitive conclusions.