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Background: Colonization by multidrug-resistant organisms (MDRO) is a frequent complication in hematologic departments, which puts patients at risk of life-threatening bacterial sepsis. Fever of unknown origin (FUO) is a condition related to the delivery of chemotherapy in hematologic malignancies, in which the use of antibiotics is debated. The incidence, risk factors, and influence on the outcome of these conditions in patients with acute myeloid leukemia (AML) are not clearly defined. Methods: We retrospectively analyzed 132 consecutive admissions of non-promyelocytic AML patients at the Hematology Unit of the University Tor Vergata in Rome between June 2019 and February 2022. MDRO swab-based screening was performed in all patients on the day of admission and once weekly after that. FUO was defined as fever with no evidence of infection. Results: Of 132 consecutive hospitalizations (69 AML patients), MDRO colonization was observed in 35 cases (26%) and resulted independently related to a previous MDRO colonization (p=0.001) and length of hospitalization (p=0.03). The colonization persistence rate in subsequent admissions was 64%. MDRO-related bloodstream infection was observed in 8 patients (23%) and correlated with grade III/IV mucositis (p=0.008) and length of hospitalization (p=0.02). FUO occurred in 68 cases (51%) and correlated with an absolute neutrophilic count <500µ/L at admission (0.04). Conclusion: In our experience, MDRO colonization is a frequent and difficult-to-eradicate condition that can arise at all stages of treatment. Prompt discharge of patients as soon as clinical conditions allow could limit the spread of MDRO. In addition, the appropriate use of antibiotics, especially in the case of FUO, and the contraction of hospitalization length, when feasible, are measures to tackle the further spread of MDRO. [ABSTRACT FROM AUTHOR]

The evolution of myeloproliferative neoplasms (MPN) to acute myeloid leukemia (AML) occurs in 2-10% of patients, depending on the MPN subtype, treatment, and follow-up length. The reverse-path from AML to MPN has been rarely reported. We herein present a 75 years old woman with AML, in whom a JAK2-V617F positive polycythemia vera (PV) emerged during follow-up, 19 months from the end of consolidation treatment. JAK2-V617F mutation screening retrospectively performed by Next Generation Sequencing (NGS) and JAK2 MutaScreen was negative on the bone marrow sample collected at AML diagnosis. However, using digital droplet PCR (ddPCR), we detected a minor JAK2 V617F mutated clone at AML onset. In addition, a TET2 R550 mutated clone persisted at stable levels throughout the disease course. This case shows that a very small MPN clone masked at AML diagnosis may expand after treatment end and be erroneously interpreted as MPN evolving from AML. Very sensitive techniques such as ddPCR may help to unravel the true disease history in these cases. [ABSTRACT FROM AUTHOR]