Inclusion Criteria:  Adult patients (> 18 years old) affected by acute leukaemia and/or recipients of bone marrow transplantation for any disease indication (during the pre and post-transplant phase) who develop febrile neutropenia, where blood cultures (and possibly bronchoscopy) are ordered as per standard of care.  Febrile neutropenia is defined as:  an ANC of <500 cells/mm3 a single temperature measurement of ≥38.0°C  Exclusion Criteria:  Patients not able to provide informed consent Death is deemed imminent