Patients will be enrolled at initiation of chemotherapy and no later than 48h from the first day of neutropenia. The same patient will be able to be enrolled more than once, but if he develops IMI, he will be no longer eligible for a subsequent inclusion. All patients will receive antimicrobial prophylaxis with fluconazole (400mg daily). Chest imaging (X-ray or CT scan) will be performed at the enrollment. During the period of neutropenia induced by chemotherapy/ conditioning regimen, patients will be surveyed for the development of fever and will have the D-index calculated day by day. At the time of febrile neutropenia, at least 2 blood cultures will be collected. Other microbiologic exams will be obtained if clinically indicated. The patients will then receive a broad-spectrum β-lactam antibiotic (cefepime). Vancomycin will be added for patients who have clinically suspicion of catheter-related infection or a blood culture yielding Gram-positive bacteria not yet identified. Serum will be obtained 3 times a week for Aspergillus GM assay (Platelia Aspergillus; Bio-Rad) and Aspergillus sp. PCR (in-house real time qualitative and quantitative PCR). A positive GM will be defined as an index ≥ 0.5.