Comparable outcomes of short-course and prolonged-course therapy in selected cases of methicillin-susceptible Staphylococcus aureus bacteremia:A pooled cohort study.

BACKGROUND The recommended duration of antimicrobial treatment for Staphylococcus aureus bacteremia (SAB) is a minimum of 14 days. We compared the clinical outcomes of patients receiving short-course (SC), 6-10 days, or prolonged-course (PC), 10-16 days, antibiotic therapy for low risk methicillin-susceptible SAB (MS-SAB). METHODS Adults with MS-SAB in 1995-2018 were included from three independent retrospective cohorts. Logistic regression models fitted with inverse probability of treatment weighting were used to assess the association between the primary outcome of 90-day mortality and treatment duration for the individual cohorts as well as a pooled cohort analysis. RESULTS A total of 645, 219 and 141 patients with low risk MS-SAB were included from Cohort I, II and III. Median treatment duration in the three SC groups were 8 days (interquartile range [IQR] 7-10), 9 days (IQR 8-10), and 8 days (IQR 7-10). In the PC groups patients received a median therapy of 14 days (IQR 13-15), 14 days (IQR 13-15) and 13 days (IQR 12-15). No significant differences in 90-day mortality were observed between the SC and PC group in Cohort I (Odds ratio [OR] 0.85, 95% confidence interval [CI] 0.49-1.41), Cohort II (OR 1.24, 95% CI 0.60-2.62) nor Cohort III (OR 1.15, 95% CI 0.24-4.019). This result was consistent in the pooled cohort analysis (OR 1.05, 95% CI 0.71-1.51). Furthermore, duration of therapy was not associated with the risk of relapse. CONCLUSION In patients with low risk MS-SAB, shorter courses of antimicrobial therapy yielded similar clinical outcomes compared to longer courses of therapy.