Intravenous Versus Oral Transition Therapy for the Treatment of Viridans Group Streptococcal Bloodstream Infections

Background: Streptococcus are amongst the most common pathogens implicated in bloodstream infections (BSI). Within the genus, S. pneumoniae and beta-hemolytic Streptococcus are the most frequently reported organisms. Viridans Group Streptococcus (VGS) have emerged as a more common cause and are associated with more severe complications. IV antibiotics have long been considered the standard of care, but recent studies have shown similar efficacy between IV and oral antibiotics. This is important because switching to oral antibiotics is associated with benefits like a shorter length of stay, decreased patient and hospital expenses, and a lower rate of adverse events. Objective: To determine if oral (PO) transition therapy is non-inferior to intravenous (IV)-only therapy for the treatment of uncomplicated Viridians Group Streptococcus (VGS) bloodstream infections (BSI). Design: Retrospective, non-inferiority cohort study. Setting: St. Luke’s University Health Network, a non-profit, academic health network. Patients: Adult inpatients with a diagnosis of VGS BSI between January 1, 2018, and December 31, 2022. Methods: Patients with VGS BSI were categorized on whether they received IV therapy for their entire treatment course or transitioned to PO therapy. The primary outcome of treatment failure was defined as a composite of all-cause mortality, hospital readmission due to infectious process, or recurrent BSI within 90 days. Secondary outcomes included the individual components of the primary outcome, adverse events, and length of stay. Non-inferiority threshold was set at 10% in the 95% CI for the difference in the proportion of patients with treatment failure between the oral transition and intravenous-only groups. Results: The primary composite outcome occurred in 20.8% of the IV group and 11.5% of the PO transition group (RR, 0.55 [95% CI 0.18 to 1.72]). Hospital length of stay was significantly longer in the IV-only group. There were no significant differences in the other outcomes. Notably, 12 of the 16 treatment-related adverse events observed in the IV-only group were associated with use of an indwelling IV catheter. Conclusions: Although the risk ratio for the composite outcome of treatment failure favors a transition to oral therapy, statistical non-inferiority could not be established.