850. Outcomes of Patients Discharged on Parenteral Ceftriaxone Compared with Oxacillin or Cefazolin in Methicillin-susceptible Staphylococcal aureus (MSSA) Bloodstream Infections

Abstract Background MSSA is a leading cause of bloodstream infection (BSI) and its incidence is on the rise. Standard of care (SOC) is prolonged parenteral therapy with nafcillin, oxacillin, or cefazolin. Ceftriaxone is active against MSSA and can be given conveniently as a daily infusion. Methods We conducted a retrospective analysis of hospitalized adults with MSSA BSI from December 2014 to May 2018, defined as ≥1 blood cultures positive for MSSA and discharged on outpatient parenteral antimicrobial therapy (OPAT) on either ceftriaxone, cefazolin, or oxacillin. We excluded patients with ESRD and polymicrobial infections. We collected demographics, comorbidities, outcome data, and treatment-related adverse events. The primary outcome was 90-day mortality with secondary outcomes of clinical failure and microbiologic failure. Clinical failure was defined as readmission for any infection within 90 days of discharge or a change in antibiotics from the planned course of therapy after discharge. Microbiologic failure was defined as reinfection with MSSA within 90 days of discharge from any site. Results In total, 167 patients had a BSI with MSSA. Of those patients, 66 (39.5%) were discharged on SOC and 101 (60.5%) on ceftriaxone. The two groups were similar in terms of their demographics (Table 1). The SOC group had more cases of endocarditis with 34 (51.5%) than ceftriaxone with 25 (24.8%) (P = 0.001). LOS for the SOC group had a median of 14.05 days whereas the ceftriaxone group had a median length of stay of 7.88 (P = 0.004). In the SOC group, 5 (7.6%) patients died compared with 8 (7.9%) patients in the ceftriaxone group within 90 days of the onset of bacteremia which was not statistically significant (P = 0.94) (Figure 1). There were 4 (6.1%) cases of microbiologic failure in SOC and 7 (6.9%) cases in the ceftriaxone group (P = 0.83). For clinical failures, the SOC had 6 (9.1%) cases compared with the 19 (18.8%) cases in the ceftriaxone group (P = 0.13). Conclusion Ceftriaxone was not statistically different when compared with SOC in terms of mortality, microbiologic failure, or clinical failure. Though clinical failures numerically were more frequent in the ceftriaxone group. Ceftriaxone maybe a reasonable and convenient option to SOC for patients with uncomplicated MSSA BSI discharged on OPAT, but further studies are needed. Disclosures All Authors: No reported Disclosures.