1096. Linezolid versus Tedizolid for the Treatment of Nontuberculous Mycobacteria in Solid Organ Transplant Recipients: An Assessment of Safety

Background Treatment options for nontuberculous mycobacteria (NTM) infections are limited by the long-term tolerability of antimicrobials. The oxazolidinones, linezolid and tedizolid, display in vitro activity against many NTM species and demonstrate excellent oral bioavailability. This study compares the hematologic safety profile of linezolid versus tedizolid for the treatment of NTM in solid organ transplant (SOT) recipients. Methods This retrospective cohort study included adult SOT recipients who received linezolid or tedizolid as part of a multi-drug regimen to treat NTM between January 1, 2010 to August 31, 2019. The primary endpoint was the hematologic effects of linezolid versus tedizolid from therapy initiation to week seven. This time frame was chosen based on the median duration of therapy. A mixed-effects ANOVA model was used to assess the effects of linezolid and tedizolid on platelet counts (PLT), absolute neutrophil counts (ANC), and hemoglobin (Hgb) across time. Subjects were treated as a random effect. The secondary analysis described the proportion of adverse effects and discontinuation. Results Twenty-four patients were included in the analysis (9 linezolid, 15 tedizolid). Mycobacterium abscessus abscessus was the most common isolate, and pulmonary was the most common site of infection (Table 1). The median duration of therapy was 24 days (range 3 to 164 days) and 48 days (range 11 to 571 days) for linezolid and tedizolid, respectively. All patients in the linezolid group received 600 mg daily or less for the majority of treatment duration. In the mixed-effects ANOVA, the ANC decreased in both groups after seven weeks of therapy (p=0.04). Otherwise, no significant effects for week, treatment group, or interaction between week and treatment group were found (Figure 1). Thrombocytopenia and neutropenia were common in both groups, and around one-fifth of patients in each group discontinued the medication due to adverse effects (Table 2). Table 1. Baseline characteristics of solid organ transplant recipients who received linezolid or tedizolid as part of a multi-drug regimen to treat nontuberculous mycobacteria infections between January 1, 2010 to August 31, 2019 at UT Southwestern Medical Center. Table 2. Adverse drug events and discontinuation of therapy over seven weeks of therapy. Figure 1. Effects of linezolid versus tedizolid during the initial seven weeks of therapy using a mixed-effects ANOVA model, (a) platelet counts, (b) absolute neutrophil counts, and (c) hemoglobin. Conclusion Non-significant statistical differences were found comparing the effects of linezolid versus tedizolid for PLT, ANC, and Hgb using mixed-effects ANOVA models. Larger cohort studies are required to compare the hematologic adverse effect profile of the oxazolidinones for the treatment of NTM infections in SOT recipients. Disclosures All Authors: No reported disclosures