177. Clinical Outcomes of Daptomycin vs. Anti-Staphylococcal β-Lactams in Definitive Treatment of Methicillin-Susceptible Staphylococcus aureus (MSSA) Bloodstream Infections

BACKGROUND: The preferred management of patients with MSSA bacteremia includes definitive therapy with intravenous anti-staphylococcal β-lactam antibiotics. In β-lactam allergic or intolerant patients, daptomycin has been targeted as a viable alternative. The objective of this study was to assess clinical outcomes of daptomycin compared with nafcillin or cefazolin for the treatment of MSSA bacteremia. METHODS: This was a retrospective cohort study of patients hospitalized from November 1, 2011 to October 31, 2018 at The Ohio State University Wexner Medical Center with MSSA bacteremia. Patients treated with nafcillin, cefazolin or daptomycin were included with 1:1:1 random selection. The primary outcome was a composite of clinical failure, defined as a change in therapy due to persistent/worsening signs and symptoms, bacteremia recurrence or persistence, or inpatient infection-related mortality. Secondary endpoints included 30-day infection-related mortality, duration of bacteremia, 30-day all-cause mortality and adverse events (AEs) necessitating a change in therapy. RESULTS: Among patients with MSSA bacteremia, 162 received at least one dose of daptomycin. Of those, 29 received at least 14 days of daptomycin and/or received daptomycin as definitive therapy and thus were included in the analysis. There was no difference in the primary outcome of composite clinical failure comparing daptomycin vs. nafcillin/cefazolin (P = 0.71). In addition, no difference was observed in 30-day infection-related mortality (P = 0.51), duration of MSSA bacteremia (P = 0.9), or 30-day all-cause mortality (P = 0.64). A higher number of AEs necessitating change in therapy were seen in the daptomycin group (P = 0.0002), reflecting initial β-lactam intolerance. CONCLUSION: No difference in clinical failure was identified in patients treated with daptomycin vs. nafcillin/cefazolin suggesting that daptomycin may serve as a non-inferior alternative for treatment of MSSA bacteremia. A higher number of AEs occurred in the daptomycin group indicating β-lactam intolerance as a primary indication for daptomycin therapy. Given the small sample size, subsequent studies are needed to further evaluate the use of daptomycin in the treatment of MSSA bacteremia. DISCLOSURES: All authors: No reported disclosures.