Impact of an interdisciplinary standard operating procedure on external ventricular drainage-associated ventriculitis and antibiotic use in intensive care unit patients: a retrospective pre–post study a retrospective pre-post study

BACKGROUND: External ventricular drainage (EVD)-associated ventriculitis is a serious complication in neurocritical care. Diagnostic uncertainty and heterogeneous infection prevention and control (IPC) practices may contribute to variable ventriculitis rates and potentially avoidable antibiotic exposure. We evaluated the impact of implementing an interdisciplinary standard operating procedure (SOP) on ventriculitis incidence and antimicrobial stewardship (ABS)-related outcomes. METHODS: We conducted a retrospective single-centre pre-post study in one intensive care unit (ICU) at Charité-Universitätsmedizin Berlin (2019-2023). Adult patients with EVDs were assigned to a pre-SOP cohort (Group 1) or a post-SOP cohort (Group 2). The SOP comprised standardized IPC protocols, an algorithm-based diagnostic workup and evidence-based anti-infective strategies. The primary endpoint was study-defined EVD-associated ventriculitis, adjudicated retrospectively using uniform criteria. Secondary endpoints included empirical antibiotic initiation, duration of therapy, antibiotic consumption, ICU length of stay (LOS), mortality, and SOP adherence. Cerebrospinal fluid (CSF) parameters and clinical signs were summarized descriptively. RESULTS: A total of 166 patients were included (pre-SOP, Group 1: n = 50; post-SOP, Group 2: n = 116). The study-defined ventriculitis rate decreased from 22% [95% CI 0.13-0.35] to 9.5% [95% CI 0.05-0.16] with an unadjusted OR 0.37 [95% CI 0.13-1.04]; p = 0.053, attenuated with an adjusted OR of 0.50 [95% CI 0.19-1.35]; p = 0.169. Incidence density declined from 21.1 to 12.0 per 1000 EVD days. Empirical antibiotic use fell from 28.0% [95% CI 17.5-41.7] to 12.9% [95% CI 8.0-20.2], corresponding to an unadjusted OR of 0.38 [95% CI 0.17-0.87] and median therapy duration decreased from 16 [95% CI 13.5-18.5] to 10 days [95% CI 6.5-13.5]. ICU LOS shortened by 4 days, while ICU mortality remained unchanged (26% vs. 27%). CONCLUSION: An interdisciplinary SOP was associated with reduced empirical antibiotic exposure and shorter treatment duration without affecting ICU mortality. The SOP appeared to improve diagnostic consistency and standardization of the workup rather than diagnostic test performance. TRIAL REGISTRATION: The study is registered in the German Clinical Trial Register (DRKS ID: 00036075) in February 2025.