212. Outcomes of Adults with Uncomplicated Staphylococcus aureus Bacteremia Receiving Short-Course Vs. Prolonged-Course Antibiotic Therapy in a Multicenter, Propensity Score–Matched Cohort

Background The recommended duration of antibiotic treatment for uncomplicated Staphylococcus aureus bloodstream infections is 14 days. We compared the outcomes of patients receiving short-course (6–10 days) vs. prolonged-course (11–16 days) antibiotic therapy for S. aureus bacteremia (SAB). Methods 30-day outcome of patients with penicillin (PSSAB, n = 202)) or methicillin-susceptible SAB (MSSAB, n = 203) treated with in vitro active therapy in the range of 6–16 days was analyzed using pooled data from two previously published, observational studies. Individuals were matched 1:1 by nearest neighbor propensity score matching without replacement. Regression analysis was performed to estimate the risk of all-cause mortality within 30 days after the end of antibiotic treatment. Eligible individuals had to have >1 day of follow-up after discontinuation of antimicrobials. Individuals with a diagnosis of endocarditis, bone infection, meningitis or pneumonia were excluded. Results There were 107 well-balanced matched pairs; 58 in the PSSAB and 39 in the MSSAB cohort. For PSSAB, the median duration of therapy was 8 (interquartile range [IQR], 7–10) in the short-course group and 12 days (IQR, 10–13) in the prolonged-course group. For the MSSAB cohort, these numbers were 9 days (IQR, 7–10) and 14 days (IQR, 13–16 days), respectively. No difference in mortality between short-course and prolonged-course treatment was observed (adjusted hazard ratio [aHR], 0.74; 95% confidence interval [CI], .23–2.41) and 1.14; 95% CI, 0.31–4.20), respectively for PSSAB and MSSAB. Conclusion Short courses of antibiotic therapy yielded similar clinical outcomes as prolonged courses of antibiotic therapy for S. aureus bacteremia. The findings warrant a randomized clinical trial to study the safety and efficacy of shortened antimicrobial therapy for the treatment of uncomplicated SAB. Disclosures All authors: No reported disclosures.