Inclusion Criteria:  Male or female, 65> =Age (years) >= 18; Newly diagnosed as AML patients according to World Health Organization (WHO) classification; Eastern Cooperative Oncology Group (ECOG) Performance status of 0,1,2; Patients will receive standard intensive chemotherapy (7+3) or bcl-2 inhibitor-based targeted therapy; Patients have not received prior therapy for AML (except hydroxycarbamide); Liver function: Total bilirubin lower than 3 upper limit of normal (ULN); Aspartate aminotransferase (AST) lower than 3 ULN; Alanine aminotransferase (ALT) lower than 3 ULN (except extramedullary infiltration of leukemia); Renal function with creatinine clearance rate (Ccr) higher than 30 ml/min; Patients who sign the informed consent must have the ability to understand and be willing to participate in the study and sign the informed consent.  Exclusion Criteria:  Acute promyeloid leukemia; AML with central nervous system (CNS) infiltration; Any history of chronic intestinal affections (Crohn disease, inflammatory bowel disease, gluten intolerance) or gastrointestinal surgery; HIV infection, Chronic hepatitis B virus (HBV) or hepatitis C (HCV) requiring treatment; Severe and active infection that is difficult to control and cannot tolerate induction therapy; Female who are pregnant, breast feeding or childbearing potential without a negative urine pregnancy test at screen; Antibiotic exposure within 30 days before enrollment (carbapenems and/or tigecycline were not included, penicillin, cephalosporins and quinolones could be included) Patients reject to participate in the study; Patients with severe heart failure (grade 3-4) or patients deemed unsuitable for enrolment by the investigator.