This is a prospective single arm study with the study period from June 1st, 2019 to May 31st, 2020. An historical control group will be used in the study, which includes all patients received HSCT but not GI panel detection between June 1st, 2018 to May 31st, 2019. All patients receiving HSCT within the year at SCMC will be enrolled in the study. The stool samples will be collected from each patient at 2-3 time points, including the day before pre-conditioning (T1), 28+-3 days after HSCT (T2), and the day severe diarrhea present (T3). All the stool samples will be detected by the FilmArray GI panel, and the results as well as other clinical information including the laboratory examinations will be recorded and analyzed.

Inclusion Criteria:

• Age ≤ 18 years old;
• Receiving HSCT;
• Legal guardians fully understand and sign informed consent.

Exclusion Criteria:

• Receiving secondary transplantation;
• Cannot give informed consent or not willing to enroll the study.

All patients receiving HSCT within the year at SCMC