Management of Cytomegalovirus Infection in Allogeneic Hematopoietic Stem Cell and in Solid Organ Transplantation: Updated Recommendations by the GITMO, SITO, SIMIT, and AMCLI Italian Societies.

New options for prevention and therapy of cytomegalovirus (CMV) infection and new tests for antiviral immune reconstitution are leading to increased complexity in the management of CMV after allogeneic hematopoietic stem cell (allo-HSCT) and solid organ transplantation (SOT) recipients. To inform the optimal care of these patients, under the auspices of the Italian GITMO, SITO, SIMIT, and AMCLI transplant, infectious, and clinical microbiology societies, we updated the guidelines published in 2019. New recommendations were produced using a consensus-building methodology after a comprehensive review of articles released from 2019 to 2025 (March). Five domains and 31 key questions were selected through a series of questionnaires using a Delphi process. The recommendations on CMV management in transplant recipients were related to diagnostics, prevention, and treatment. Key recommendations include: in both allo-HSCT and SOT, donor and recipient should be evaluated for anti-CMV serological status before transplant for risk stratification; monitoring of CMV infection after transplant should be performed by assaying CMV DNAemia with real time PCR; CMV-specific cell mediated immunity should be monitored after transplantation in allo-HSCT and SOT; in CMV seropositive adult allo-HSCT recipients with negative CMV DNAemia, letermovir prophylaxis is recommended; there is no mandatory indication to universal prophylaxis in SOT recipients; preemptive antiviral therapy is recommended in patients with clinically significant CMV infection (CS-CMV-i); in patients with resistant or refractory CMV infection or disease after first-line antiviral therapy, oral maribavir is recommended as second line antiviral therapy. In conclusion, these recommendations aim to guide clinical practice and improve outcomes in this high-risk population.