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.