(477) Evaluation of Prophylactic Antibiotic Regimens for Penetrating Brain Injuries in the ICU

Introduction: Penetrating traumatic brain injuries (pTBI) constitute high mortality. Civilian pTBI has a 66-90% mortality pre-hospital and >50% afterwards. Patients without antibiotics are anticipated to have an infection rate of 8-30% & 1-33.9% with antibiotics use. However, these studies are confounded by heterogeneity in treatment regimens, small sample sizes, practice variations, observational duration and lack of formal guidelines. We aimed to characterize antibiotic choices, infection incidence & pathogens to form an institutional protocol.

Methods: This IRB exempt retrospective case series evaluated patients from June 2021-March 2023 at a level 1 trauma center. Subjects were identified by the trauma registry's Abbreviated Injury Score (AIS) as having a pTBI. Inclusion criteria involved admission to the ICU, not deceased < 72 hrs after admission & administration for any antibiotic for pTBI related prophylaxis. Exclusion criteria included subjects: with an underlying immunosuppressive disorder, transferred from another facility with incomplete data, whose antibiotics were only initiated for any other indication, whose antibiotics are withdrawn for comfort measures. Basic statistics were conducted.

Results: Of 56 qualifying admissions, 17 met the inclusion criteria. Death < 72 hrs of arrival caused exclusion of 36/39 patients. GSW constituted the mechanism of injury for 14/17 patients. There were no positive wound, CSF or blood cultures resulting from this injury & only 2 patients later got a CSF PCR. Antibiotic regimens were vancomycin plus metronidazole & either cefazolin (6%), ceftriaxone (35%) or cefepime (59%). Antibiotic duration was 24hrs-10 days. There were no recorded concerns or objective data to support incidence of antibiotic induced adverse effects for any of these patients. Mortality occurred for 4 (23.5%) patients & the median time to mortality was 5.32d (3.27–9.46). Median ICU LOS was 4.6d (1.3-25.9), while hospital was 16.87d (3.43-104.64).

Conclusions: More recent studies evaluating this indication have not demonstrated a clinical need. Clinical suspicion in this group was low, with all patients only getting routine infection screening upon ICU admission. Antibiotic regimens can likely be consolidated into shorter, protocolized durations such as vancomycin and ceftriaxone for 72 hrs.