Short Antibiotic Treatment in High Risk Febrile Neutropenia

Inclusion Criteria: 1. Age 18 years and older. 2. The patient either has acute leukemia (AML, ALL or mixed-phenotypic acute leukemia) and is undergoing induction, re-induction or salvage chemotherapy or undergoing allogeneic HSCT and receiving conditioning chemotherapy and/or radiation. 3. Documented febrile neutropenia as defined by the IDSA guidelines \[1\]: 1. Single oral temperature of ≥38.3°C or at least two measurements of ≥38.0°C in an interval of ≥1 hour. 2. ANC ≤ 0.5x109/L. 4. Patient without a clinically or microbiologically documented infection (CDI/MDI). We will require the following criteria to rule out infection: 1. No focus of infection on a thorough history and physical examination at baseline and daily. 2. Negative blood cultures after at least two sets of blood cultures have been taken. For example, the growth of coagulase-negative staphylococci, diphtheroids or Bacillus spp. from a single set will be considered contamination if another set of blood cultures is negative. Therefore, additional blood cultures will be taken in this case. 3. Other cultures will be taken as indicated. 4. A negative chest XR or CT scan (which will be performed according to the physician's discretion) for patients with symptoms of cough or chest pain. 5. The subject will comply with the following criteria: 1. Received empirical antibiotics for at least 72 hours AND 2. Is afebrile for at least 24 hours AND 3. Is still neutropenic (ANC ≤0.5x109/L). Exclusion Criteria: 1. Concurrent participation in another interventional trial. 2. The patient has received empirical antibiotics for more than seven days from the onset of the febrile neutropenic episode. 3. Septic shock at the onset of the episode or 72 hours (defined as persisting hypotension requiring vasopressors to maintain a MAP ≥ 65 mmHg and having a serum lactate level \> 2 mmol/L despite adequate volume resuscitation). 4. Patients with febrile neutropenia secondary to the treatment for solid malignancies, autologous HSCT, CAR-T cell therapy, hematologic malignancies besides acute leukemia when not in the context of allogeneic HSCT, AML treated with consolidation chemotherapy, or ALL treated with intensification and maintenance phase of chemotherapy. 5. Clinically or microbiologically documented infections except for probable or proven invasive fungal disease diagnosed a-priori and treated. 6. Patients receiving their induction chemotherapy or allogeneic HSCT as outpatients. 7. We will not allow the enrollment of patients who have been previously enrolled in this study.