Outcomes of allogeneic hematopoietic cell transplantation in patients with carbapenem-resistant organisms infection: a propensity score-matched analysis.

Background: Carbapenem-resistant organisms (CRO) cause significant morbidity and mortality, with a rising incidence worldwide. Immunosuppression, prolonged hospitalization, and extensive use of broad-spectrum antibiotics make allogeneic hematopoietic cell transplant (alloHCT) recipients particularly susceptible. This study evaluated the impact of peri-transplant CRO infections on alloHCT outcomes. Methods: We conducted a retrospective analysis of adult alloHCT recipients between 2015 and 2024. CRO infection was defined as occurring within 12 months of alloHCT. Using 1:3 propensity score matching, patients with CRO were matched to controls by age, sex, year of transplant, stem cell source, donor type, and diagnosis. Overall survival (OS) and non-relapse mortality (NRM) were analyzed using Kaplan-Meier methods and Cox proportional hazards models. Results: A total of 171 patients were included: 43 with CRO and 128 controls; 53.4% of CRO cases occurred in the last 3 years. Median age was 35 years, 66.7% were male, and 89.5% underwent transplant for malignant disease. Matched-related donors were used in 79.5%, peripheral blood stem cells in 88.3%, and myeloablative conditioning in 70.2%. Median follow-up was 27 months. CRO patients had higher ICU admission rates (30.2% vs. 17.2%, Conclusions: CRO infections remain an increasing challenge in alloHCT and are associated with higher ICU admission, increased NRM, and inferior survival, highlighting the need for improved prevention and management strategies.