Efficacy of Enhanced Antimicrobial Stewardship Team Interventions for Patients Receiving Meropenem and Tazobactam/Piperacillin

Multidrug-resistant bacteria pose a major challenge in healthcare, and antimicrobial stewardship teams (ASTs) play a crucial role in optimizing antimicrobial use, particularly for last-resort drugs like meropenem (MEPM) and tazobactam/piperacillin (TAZ/PIPC). This study evaluated the impact of enhanced interventions, which included a hospital-wide policy restricting MEPM and TAZ/PIPC use to 5 d and mandating pre-treatment culture testing. A before-and-after study was conducted at a public hospital in Japan, comparing the pre- (June 2021-May 2022) and post-enhanced intervention (June 2022-May 2023) periods. The primary outcome was days of therapy (DOT) per 1000 patient days for MEPM and TAZ/PIPC. Secondary outcomes included antimicrobial use density (AUD), monthly number of patients receiving MEPM and TAZ/PIPC, 30-d mortality, and AST intervention proposals. Overall, 1896 patients received MEPM (pre: 591; post: 527) or TAZ/PIPC (pre: 411; post: 367). As a result, MEPM DOT decreased from 19.4 to 17.2 per 1000 patient days (p = 0.019), and AUD from 14.4 to 11.7 defined daily doses per 1000 patient days (p = 0.017). TAZ/PIPC DOT remained unchanged (p = 0.219), while AUD decreased from 8.7 to 7.6 (p = 0.046). Furthermore, the monthly number of patients receiving MEPM and TAZ/PIPC and their 30-d mortality showed no significant change. AST proposals increased from 209 to 359 for MEPM and from 116 to 238 for TAZ/PIPC (both p < 0.001). In conclusion, enhanced interventions effectively reduced MEPM use without increasing TAZ/PIPC use or worsening 30-d mortality, suggesting that structured guidelines may enhance antimicrobial stewardship in resource-limited settings.