Oral Antibiotics for Treatment of Gram-Negative Bacteremia in Solid Organ Transplant Recipients: A Propensity Score Weighted Retrospective Observational Study

Abstract Background We assessed the safety and efficacy of oral antibiotic step-down therapy for uncomplicated gram-negative blood stream infections in solid-organ transplant recipients. Methods We identified all solid-organ transplant recipients within the Massachusetts General and Brigham and Women's Hospital systems from 2016 to 2021 with uncomplicated gram-negative bacteremia involving an organism susceptible to an acceptably bioavailable oral antibiotic agent. Using inverse probability of treatment-weighted models based on propensity scores adjusting for potential clinical confounders, we compared outcomes of those transitioned to oral antibiotics with those who continued intravenous (IV) therapy for the duration of treatment. Primary endpoints were mortality, bacteremia recurrence, and reinitiation of IV antibiotics. Secondary endpoints included length of stay, Clostridioides difficile infection, treatment-associated complications, and tunneled central venous catheter placement. Results A total of 120 bacteremia events from 107 patients met inclusion criteria in the oral group and 42 events from 40 patients in the IV group. There were no significant differences in mortality, bacteremia recurrence, or reinitiation of IV antibiotics between groups. Patients transitioned to oral antibiotics had an average length of stay that was 1.97 days shorter (95% confidence interval [CI], −.39 to 3.56 days; P = .005). Odds of developing C. difficile and other treatment-associated complications were 8.4 times higher (95% CI, 1.5–46.6; P = .015) and 6.4 times higher (95% CI, 1.9–20.9; P = .002), respectively, in the IV group. Fifty-five percent of patients in the IV group required tunneled catheter placement. There was no difference in treatment duration between groups. Conclusions Oral step-down therapy was effective and associated with fewer treatment-related adverse events.