574. De-escalation of Broad Spectrum Antibiotics during Cytokine Release Syndrome with Haploidentical Hematopoietic Stem Cell Transplantation

BACKGROUND: Fever is a common component of cytokine release syndrome (CRS) occurring in 90% of patients undergoing haploidentical hematopoietic stem cell transplantation (Haplo-HSCT). Fevers typically occur between the stem cell infusion (Day 0) and initiation of post-transplant cyclophosphamide and are often confused with febrile neutropenia (FN). Due to longer time to engraftment in Haplo-HSCT, CRS/FN exposes patients to prolonged courses of empiric broad spectrum antibiotic (BSA) therapy increasing the risk for multi-drug resistant organisms. Recently, at Yale New Haven Health, our practice has changed to now recommend antibiotic de-escalation to prophylaxis after 7 days of BSA if no infection is identified. The objective of this study was to assess the incidence of breakthrough infections with the de-escalation of BSA in CRS/FN. Secondary endpoints include rate of FN, rate of de-escalation, rate of recurrent fevers, duration of BSA, and positive blood culture data. METHODS: The patient population included those undergoing Haplo-HSCT between July 2016 and February 2020 and who developed CRS/FN between Day 0 and Day +5. Patients were excluded if they had prolonged hospitalization due to non-infectious complications or engraftment failure. Bacteremia was defined using NHSN definitions. RESULTS: Of the 53 Haplo-HSCTs assessed, 43 experienced CRS/FN. Thirty-five Haplo-HSCT (81%) with CRS/FN had negative cultures and 23 (66%) of these were de-escalated back to antibacterial prophylaxis. The median duration of BSA in the de-escalated group was 7 days (range 5–13) compared to 16.5 days range (13–21) in the non-de-escalated group (p< 0.001). Among those de-escalated, 7 (30%) had recurrent fever occurring at a median of 4 days (range 2–14) and were placed back on BSA. Two Haplo-HSCT (9%) that had fever after de-escalation developed a breakthrough bacteremia. No Haplo-HSCT after de-escalation had fever or re-admission for bacteremia 30 days after engraftment. Four Haplo-HSCT (9%) with CRS/FN had positive blood cultures; however, three (7%) were still able to be de-escalated from BSA to narrower agents based on susceptibilities. CONCLUSION: De-escalation of BSA in FN/CRS in Haplo-HSCT patients reduced unnecessary, prolonged antibiotic exposure with a low incidence of breakthrough infections. DISCLOSURES: All Authors: No reported disclosures