Comparison of Oral and Intravenous Definitive Antibiotic Therapy for Beta-Hemolytic Streptococcus Species Bloodstream Infections from Soft Tissue Sources: a Propensity Score-Matched Analysis

Beta-hemolytic streptococci are common causes of bloodstream infection (BSI). There is emerging data regarding oral antibiotics for BSI but limited for beta-hemolytic streptococcal BSI. We conducted a retrospective study of adults with beta-hemolytic streptococcal BSI from a primary skin/soft tissue source from 2015 to 2020. Patients transitioned to oral antibiotics within 7 days of treatment initiation were compared to those who continued intravenous therapy, after propensity score matching. The primary outcome was 30-day treatment failure (composite of mortality, infection relapse, and hospital readmission). A prespecified 10% noninferiority margin was used for the primary outcome. We identified 66 matched pairs of patients treated with oral and intravenous antibiotics as definitive therapy. Based on an absolute difference in 30-day treatment failure of 13.6% (95% confidence interval 2.4 to 24.8%), the noninferiority of oral therapy was not confirmed (P = 0.741); on the contrary, the superiority of intravenous antibiotics is suggested by this difference. Acute kidney injury occurred in two patients who received intravenous treatment and zero who received oral therapy. No patients experienced deep vein thrombosis or other vascular complications related to treatment. In patients treated for beta-hemolytic streptococcal BSI, those who transitioned to oral antibiotics by day 7 showed higher rates of 30-day treatment failure than propensity-matched patients. This difference may have been driven by underdosing of oral therapy. Further investigation into optimal antibiotic choice, route, and dosing for definitive therapy of BSI is needed. Beta-hemolytic streptococci are common causes of bloodstream infection (BSI). There is emerging data regarding oral antibiotics for BSI but limited for beta-hemolytic streptococcal BSI.