摘要Background Diarrhea is a common complication of hematopoietic stem cell transplantation(HSCT)and is associated with substantial morbidity,but its etiology is often unknown.Etiologies of diarrhea in this population include infectious causes,chemotherapy-or medication-induced mucosal injury and graft-versus-host disease(GVHD).Distinguishing these poten-tial causes of diarrhea is challenging since diarrheal symptoms are often multifactorial,and the etiologies often overlap in transplant patients.The objectives of this study were to evaluate whether the FilmArray gastrointestinal(GI)panel would increase diagnostic yield and the degree to which pre-transplantation colonization predicts post-transplantation infection.Methods From November 2019 to February 2021,a total of 158 patients undergoing HSCT were prospectively included in the study.Stool specimens were obtained from all HSCT recipients prior to conditioning therapy,28±7 days after trans-plantation and at any new episode of diarrhea.All stool samples were tested by the FilmArray GI panel and other clinical microbiological assays.Results The primary cause of post-transplantation diarrhea was infection(57/84,67.86％),followed by medication(38/84,45.24％)and GVHD(21/84,25.00％).Ninety-five of 158 patients were colonized with at least one gastrointestinal patho-gen before conditioning therapy,and the incidence of infectious diarrhea was significantly higher in colonized patients(47/95,49.47％)than in non-colonized patients(10/63,15.87％)(P＜0.001).Fourteen of 19(73.68％)patients who were initially colonized with norovirus pre-transplantation developed a post-transplantation norovirus infection.Twenty-four of 62(38.71％)patients colonized with Clostridium difficile developed a diarrheal infection.In addition,FilmArray GI panel testing improved the diagnostic yield by almost twofold in our study(55/92,59.78％vs.30/92,32.61％).Conclusions Our data show that more than half of pediatric patients who were admitted for HSCT were colonized with vari-ous gastrointestinal pathogens,and more than one-third of these pathogens were associated with post-transplantation diarrhea.In addition,the FilmArray GI panel can increase the detection rate of diarrheal pathogens in pediatric HSCT patients,but the panel needs to be optimized for pathogen species,and further studies assessing its clinical impact and cost-effectiveness in this specific patient population are also needed.