Acute myeloid leukemia (AML) patients are prone to blood stream infection (BSI) due to bone marrow suppression, oral and gastrointestinal mucositis, endovascular tubes, and the application of a large number of broad-spectrum antibiotics. The associated mortality rate is as high as 7.1 %-42%. The use of antibiotics within one hour after the first observation of hypotensive symptoms can guarantee a 79.9% survival rate. For every hour of delay, the patient's survival rate will drop by 7.6%. At present, the blood culture test cycle is long and the positive rate is low. Other infection-related indicators (PCT, CRP) or next-generation sequencing are not highly specific and easy to be misdiagnosed. X-ray, CT and other examinations only have a certain auxiliary value for the infected site. We need new diagnostic tools to accurately identify pathogens. Nano-seq is a next-generation sequencing technology for single-molecule, real-time sequencing and analysis. With ultra-long sequencing read length, it can quickly and accurately identify BSI pathogens types, and give appropriate drug sensitivity results based on drug resistance genes to meet the needs of 99.9% pathogen screening. At the same time, we hope to conduct a prospective evaluation to target high-risk groups of AML prone to BSI in the early stage. The intestine is the body's largest immune organ and the largest reservoir of microbial pathogens. The expansion of certain gut microbiota usually precedes BSI. If there is a correlation between the gut microbiota and MDR-BSI, the colonization and changes of the intestinal flora can be used to predict the risk of BSI in patients during treatment, and preventive measures such as early decolonization or biological intervention will reduce the risk of infection in the future. Combined with Nano-seq and various existing clinical pathogen detection technologies to reduce the occurrence and progress of clinical BSI.

For AML patients with bloodstream infections, we analyzed and compared the sensitivity, specificity, and consistency of Nano-seq and traditional blood culture tests, and evaluated the advantages of Nano-seq for clinical diagnosis and treatment guidance of newly-treated AML bloodstream infections. At the same time, the homology analysis of gut microbiota and bloodstream infection strains was carried out to explore the correlation between gut microbiota and bloodstream infection in newly treated AML patients.

Inclusion Criteria:

• Newly diagnosed AML according to the WHO (2016) classification of acute myeloid leukemia.
• No history of previous chemotherapy or target therapy.
• Neutrophil deficiency (ANC<0.5x10^9/L) with the first time fever(Oral temperature >=38.3 degree C or axillary temperature >=38.0 degree C) accompanied by chills or hemodynamic instability(BP <=90/60mmHg）
• Ability to comprehend the investigational nature of the study and provide informed consent.

Exclusion Criteria:

• Patients have a history of chemotherapy or target therapy.
• Patients with other commodities that the investigators considered not suitable for the enrollment.

Newly diagnosed acute myeloid leukemia patients with neutropenia and bloodstream infection