2250. Combination Vancomycin Plus Cefazolin for Methicillin-Resistant Staphylococcus aureus Bloodstream Infections

BACKGROUND: Combination β-lactam and vancomycin (VAN) prevent the emergence of resistance and result in synergistic antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) in vitro. We sought to provide clinical translation to these data and determine if patients with MRSA bloodstream infection (BSI) treated with VAN + cefazolin (VAN/CFZ) via our MRSA BSI clinical pathway had improved clinical outcomes compared VAN alone. METHODS: Multicenter, retrospective, comparative cohort study from 2006 to 2019 in adults with MRSA BSI treated with VAN for ≥ 72 hours. VAN/CFZ was defined as VAN + CFZ within ≤ 72 hours of index culture for ≥ 24 hours. Other β-lactams were allowed for < 48 h in the VAN/CFZ group. The VAN alone group could not have other β-lactams within 7 days of treatment initiation. The primary outcome was clinical failure defined as a composite of 30-d all-cause mortality, 60-day recurrence, and persistent BSI (≥ 7 days). The independent effect of VAN/CFZ on clinical failure was evaluated with multivariable logistic regression. The primary safety endpoint was nephrotoxicity within 7 days of treatment initiation. RESULTS: A total of 237 patients were included (104 VAN/CFZ, 133 VAN). The most common BSI sources were skin/soft tissue (29.1%), IV catheter (21.9%), osteoarticular (20.3%) and infective endocarditis (16.0%). Demographic and clinical characteristics were similar between groups except VAN/CFZ had a higher median APACHE II score (18 vs. 13, P = 0.011). VAN/CFZ patients were also more likely to have received an infectious disease consult (100% vs. 81.2%, P < 0.001). Median (IQR) duration of CFZ was 115 (87–164) hours. After controlling for age, APACHE II score, ID consult and infection source, VAN/CFZ was associated with reduced odds of clinical failure (aOR 0.425, 95% CI 0.228, 0.792). Bivariate outcomes are shown in the table: CONCLUSION: Patients with MRSA BSI treated with VAN/CFZ vs. VAN experienced fewer clinical failures, supporting additional studies evaluating the role of adjuvant CFZ for MRSA BSI. [Image: see text] DISCLOSURES: All authors: No reported disclosures.