1808. Treatment Adherence and Outcomes Associated with Partial Oral Therapy vs. Intravenous Therapy in Patients with Serious Staphylococcus aureus Infections: A Comparative Effectiveness Study

Abstract

Abstract Background Randomized trials found oral step-down therapy to be as effective as intravenous (IV) therapy for infective endocarditis and bone and joint infections. However, the comparative effectiveness of IV versus oral step-down therapy for deep seated Staphylococcus aureus infections outside of the clinical trial setting is unknown. The objectives of this study were to compare treatment adherence and clinical outcomes between these two approaches in clinical practice. Methods This was a retrospective comparative effectiveness study involving adults hospitalized at an academic, safety net hospital between January 2019 to June 2021 with bacteremia, endocarditis, osteomyelitis, or septic arthritis due to S. aureus. Based on initial treatment plans, patients were categorized and analyzed in two groups: all IV or IV followed by oral step-down therapy. The co-primary outcomes were antibiotic adherence (percent of planned course received) and the proportion who completed therapy. The key secondary outcome of clinical failure was a composite of all-cause mortality, recurrent or new metastatic site of S. aureus infection, or requirement of an unplanned source control procedure. Results Of 249 patients included, 101 were in the all IV and 148 were in the oral step-down groups. Indications for treatment were osteomyelitis (72%), complicated bacteremia (25%), endocarditis (22%), septic arthritis (11%), and uncomplicated bacteremia (8%). Active substance abuse was observed in 43% of the IV group and 55% in the oral group. Between the all IV and oral step-down groups, antibiotic adherence rates did not differ significantly (Table); antibiotic therapy was completed by 93% vs 87% of patients (p = 0.13), respectively. Clinical failure occurred in 25% of the all IV group and 26% of the oral step-down group (p = 0.87). The frequency of other secondary outcomes was similar between groups; however, hospital length of stay was significantly longer in the IV group (Table). Table 1 Note: data presented as n (%) unless otherwise specified *within 6 months of hospital admission date for index infection Conclusion In clinical practice, oral step-down therapy for serious S. aureus infections was associated with similar rates of treatment adherence and completion, clinical outcomes and less health care resource utilization compared with IV therapy. Our findings support use of oral step-down therapy as an effective alternative to IV therapy. Disclosures All Authors: No reported disclosures.