Neutropenia is very common in patients received hematopoietic stem cell transplantation, with median duration of about 14 days. Almost all neutropenia will suffer from febrile without prophylactic antibiotics. IDSA recommended fluoroquinolones as prophylaxis in neutropenia patients of high risks, while in China, major pathogens possess high resistance to fluoroquinolones. It is not clear whether prophylaxis is of benefit, nor the appropriate prophylaxis regimen.

The current study will evaluate the three different regimen:

1. No prophylaxic antibiotic
2. Piperacillin as prophylaxis for neutropenia patients. Piperacillin has anti-pseudomonas activity.
3. Piperacillin/tazobactam as prophylaxis for neutropenia patients. Piperacillin/tazobactam has highest susceptibility rate among common anti-pseudomonas antibiotics.

1. Swab culture (skin, pharyngeal, nasal, anus) when administered into laminar flow room after transplantation.
2. Randomize the neutropenia patients into 3 groups.
3. Receive 3 regimen.
4. Full record of clinical data, including background diseases, previous antibiotics within 90 days, febrile or not at the TOC.
5. For patients developed febrile, imipenem will be prescribed, even if the patient received no prophylaxis. At the same time, the follow-up ended.

Inclusion Criteria:

• Age 13-65 years
• Received Autologous or Allogeneic hematopoietic stem cell transplantation.
• ECOG score 0-1.
• ICF is available.

Exclusion Criteria:

• Allergic to any therapy drug.
• Documented infection before neutropenia.
• Renal dysfunction.
• Suffering from central nervous system or mental disease.