(647) Antimicrobial Stewardship Impact on the Treatment of Intra-Abdominal Infections in the SICU

Introduction: Broad spectrum antibiotics are utilized for complicated intra-abdominal infection (cIAI); however, the need for empiric methicillin-resistant staphylococcus aureus (MRSA) coverage is not clear as the incidence of MRSA cIAI is rare.

Methods: A single-center, retrospective, pre- and post-cohort study of adults admitted to the Surgical Intensive Care Unit (SICU) with cIAI between March 1, 2021 to May 1, 2023 was conducted. Historically, the SICU utilized vancomycin for all cIAI; however, in April 2022 the preferred regimen was changed to either piperacillin-tazobactam with vancomycin added for patients with MRSA risk factors or for Enterococcus coverage in cefepime or levofloxacin-based regimens for penicillin allergic patients. The primary outcome was number of vancomycin days of therapy (DOT) per 1000-days present. Categorical and continuous variables were analyzed with Chi-Square and Fisher’s exact test.

Results: A total of 142 SICU encounters were included, 64 in the pre-cohort and 78 in the post-cohort. Patients in the pre- and post-cohort received a median vancomycin DOT per 1000 patient day of 14 days [IQR 5-21] compared with 16 days [IQR 8-17] (p = 0.522). There was a significant reduction in number of patients given vancomycin after the protocol change (90.6%; 6.9%, p = 0.042). A significant increase in piperacillin-tazobactam exposure was also observed (48.4%; 82.1%, p < 0.001).

Conclusions: In critically ill surgical patients with cIAI, the implementation of an antimicrobial stewardship guideline did not reduce vancomycin DOT per 1000 patient days, however, it did result in a significant reduction in vancomycin exposure.