Empiric Imipenem/Cilastatin/Relebactam for Febrile Neutropenia After Allogeneic Hematopoietic Stem Cell Transplantation: Two Case Reports

Febrile neutropenia develops in approximately three-quarters of recipients of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Among them, carbapenem-resistant Enterobacterales (CRE) associated mortality reaches up to 70%. Thus, rapid identification of CRE-high-risk patients and prompt empiric CRE coverage are critical. Two allo-HSCT recipients whose febrile neutropenia persisted on empiric carbapenem were promptly escalated to imipenem/cilastatin/relebactam, alone or combined with aztreonam and tigecycline-before culture confirmation. Defervescence occurred within 24-48 h, inflammatory markers declined progressively, and clinical infection control was achieved. Successful neutrophil and platelet engraftment followed. Immediate empiric imipenem/cilastatin/relebactam for CRE-high-risk allo-HSCT recipients with febrile neutropenia rapidly controlled infections and permitted successful hematopoietic recovery. Prospective studies are warranted.