272. Clinical Outcomes with Continuation of Combination Antibiotic Therapy versus De-escalation to Monotherapy for Patients with MRSA Bacteremia

Background Persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia is associated with increased morbidity and mortality. Previous studies have demonstrated lower mortality with combination therapy (CT) compared to monotherapy (MT) for MRSA bacteremia; however, there is a lack of evidence to favor continued CT over de-escalation to MT for completion of treatment after clearance of bacteremia. Methods This was a single-center, retrospective study at The Ohio State University Wexner Medical Center in patients with MRSA bacteremia from November 2011 to July 2019. The primary composite outcome included inpatient infection-related mortality, 60-day readmission and 60-day bacteremia recurrence in patients receiving daptomycin and ceftaroline CT for greater than 10 days against those who received three to ten days of CT and were then de-escalated to either daptomycin, ceftaroline, or vancomycin MT. Statistical analysis used simple and multivariate logistic regression models to estimate crude and adjusted odds ratios and the 95% confidence interval to assess the relationship between the composite outcome for the MT and CT groups, while controlling for proven cofounders. Results A total of 286 patients with MRSA bacteremia were identified with 146 patients omitted based on exclusion criteria. The study population included 66 in the CT group and 74 in the MT group. Of those in the MT group 20 received ceftaroline, 29 received daptomycin, and 25 received vancomycin. Median age was 46 years (IQR 34.5–61), 60% required intensive care unit stay (n=84), and patients were 51% female (n=71) and 78% white (n=109). Bacteremia source was primarily intravenous drug use (40%) or line-related (16%). No significant difference was observed in the primary composite outcome (21% CT group vs 24% MT group; p=0.66). Within this outcome, there was no significant difference in readmission within 60 days (20% CT group vs 18% MT group; p=0.75), bacteremia recurrence within 60 days (3% CT group vs 7% MT group; p=0.45), or inpatient infection-related mortality (2% CT group vs 5% MT group; p=1.00). Conclusion No significant difference was found in the composite clinical outcome for MRSA bacteremia patients with continued CT versus those who were switched to MT. Disclosures All Authors: No reported disclosures