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; 11–16 days) antibiotic therapy for low-risk methicillin-susceptible SAB (MS-SAB). Methods Adults with MS-SAB in 1995–2018 were included from 3 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 cohorts I, II, and III. Median treatment duration in the 3 SC groups was 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}, .49–1.41]), cohort II (OR, 1.24 [95% CI, .60–2.62]), or cohort III (OR, 1.15 [95% CI, .24–4.01]). This result was consistent in the pooled cohort analysis (OR, 1.05 [95% CI, .71–1.51]). Furthermore, duration of therapy was not associated with the risk of relapse. Conclusions In patients with low-risk MS-SAB, shorter courses of antimicrobial therapy yielded similar clinical outcomes as longer courses of therapy.