2402. Evaluating Clinical Outcomes of Adjunctive Beta-Lactam Use in Vancomycin-Resistant Enterococcus Infective Endocarditis

BACKGROUND: Vancomycin resistant enterococcus (VRE) infective endocarditis (IE) is associated with poor outcomes. There are limited data to guide the antimicrobial choice and duration of therapy. Several in vitro and limited clinical studies demonstrate the synergistic effect of β-lactams with other agents, particularly daptomycin, in this setting. We sought to compare clinical outcomes in patients with VRE IE treated with adjunctive β-lactam therapy. METHODS: This was an IRB-approved, retrospective, single-center cohort study. The study included patients ≥18 years of age diagnosed with VRE IE via modified Duke criteria from 2011-2021. Data were collected by electronic medical record review. Descriptive statistics were obtained. The primary outcome was 90-day treatment failure compared between those receiving and not receiving adjunctive β-lactams. Treatment failure was defined as recurrence of bloodstream infection (BSI) or death within 90 days of diagnosis. Failure-free survival was analyzed by Kaplan-Meier curve with log-rank test. RESULTS: A total of 32 cases were identified. 12 received adjunctive β-lactams. Mean age was 67 years, and 71% were male. 13 (41%) had a prosthetic valve and 6 (19%) had a CIED (Table 1). A majority (78%) had E. faecium IE. Mean duration of bacteremia was 9 days (Table 2). About one-third had treatment failure with 7 deaths and 4 BSI recurrences. Adjunctive β-lactams included ampicillin (3), cefepime (1), ceftaroline (6) and ceftriaxone (2). There was no statistical difference in failure-free survival in patients treated with adjunctive β-lactam therapy (Figure 1). The results were similar when restricted only to those who received daptomycin with or without adjunctive β-lactam therapy. [Figure: see text] [Figure: see text] Figure 1. [Figure: see text] Kaplan-Meier curve comparing failure-free survival between patients who were primary treated with adjunctive β-lactams versus non-adjunctive therapy. The p-value is calculated via the log-rank test. CONCLUSION: VRE IE is associated with poor prognosis, including high rates of mortality and relapses. In our experience, adjunctive B-lactam use did not result in improved outcome. Limitations include small sample size, and heterogenous antibiotic use. More prospective randomized data are needed. DISCLOSURES: All Authors: No reported disclosures