Clinical Outcomes of Daptomycin Versus Anti-Staphylococcal Beta-Lactams in Definitive Treatment of Methicillin-susceptible Staphylococcus aureus Bloodstream Infections

Staphylococcus aureus (S. aureus) is the leading cause of bacteraemia and infective endocarditis worldwide. The preferred management of patients with methicillin-susceptible S. aureus (MSSA) bacteraemia includes definitive therapy with intravenous anti-staphylococcal beta-lactam (ASBL) antibiotics. Daptomycin (DAP) has been targeted as a viable substitute for beta-lactam allergic or intolerant patients. This single-center retrospective cohort study assessed clinical outcomes of DAP compared with ASBL antibiotics [nafcillin (NAF) or cefazolin (CFZ)] for the treatment of MSSA bacteraemia in patients hospitalised from 01 November 2011 to 31 October 2018. The primary outcome was a composite of the following: clinical failure, MSSA recurrence and MSSA persistence or inpatient infection-related mortality. Secondary outcomes included duration of MSSA bacteraemia, infection-related length of stay, infection-related 90-day readmission, 30-day all-cause mortality, and adverse events necessitating a change in therapy. Of 89 patients with MSSA bacteraemia who were included: 29 received DAP, 30 received NAF and 30 received CFZ. There was no difference in the composite primary outcome in patients treated with DAP compared with ASBL (10% vs. 5%, P = 0.39). The DAP cohort had a longer hospital length of stay compared with the ASBL group (20 days vs. 11.5 days, P = 0.0007). No differences were detected between other secondary outcomes. This study suggests that DAP may serve as a comparable alternative to ASBLs for treatment of MSSA bacteraemia, as no differences in clinical outcomes were identified. Larger studies are needed to confirm these findings.