Sequential intravenous-to-oral outpatient antibiotic therapy for MRSA bacteraemia: one step closer.

Background: Published guidelines call for prolonged courses of intravenous (iv) antibiotics for the treatment of MRSA bloodstream infection (BSI) to ensure eradication of deep foci and decrease relapse risk. Sequential iv-to-oral antibiotic therapy has been successfully applied to other serious infections but has not been evaluated for MRSA BSI. Objectives: To compare outcomes in adults completing MRSA BSI therapy with oral versus parenteral antibiotics in the outpatient setting [oral outpatient antibiotic therapy (00AT) versus outpatient parenteral antibiotic therapy (OPAT)]. Methods: This was a single-centre, retrospective, cohort study between 2008 and 2018. The primary outcome was 90 day clinical failure (MRSA BSI recurrence, deep-seated MRSA infection or all-cause mortality). Analyses were adjusted for confounding using inverse probability of treatment weighting (IPTW). Results: A total of 492 patients were included (70 00AT, 422 OPAT). In general, 00AT patients had characteristics consistent with a lower risk of poor outcomes; however, after IPTW key prognostic factors were balanced. In IPTW-adjusted analysis, there was non-significant reduction in the rate of 90 day clinical failure in the 00A] group compared with the OPAT group [adjusted HR (aHR) 0.379, 95% CI 0.131-1.101]. In analyses restricted to pre-specified subgroups defined by index infection complexity and comorbidity burden, findings were consistent with the main analysis. Furthermore, 00AT patients had a significantly reduced rate of 90 day hospital readmission (aHR 0.603, 95% CI 0.388-0.937). Conclusions: We provide preliminary evidence that selected patients with MRSA BSI may have at least equivalent clinical outcomes with 00AT versus OPAT and provide support to ongo ng and future studies evaluating oral antibiotics for MRSA BSI.