Understanding gut Microbiome changes in Korean children, adolescents, and young adults with hematologic malignancies.

We investigated whether changes in the gut microbiome composition are associated with infections and immunologic complications during the treatment of Korean children, adolescents, and young adults (AYAs) with hematologic malignancies. We analyzed stool samples from 26 patients and 10 healthy siblings using 16 S rRNA gene sequencing. At diagnosis, patients exhibited a lower abundance of Lachnospiraceae and a higher abundance of Enterococcaceae than their healthy siblings. Both the Chao1 and Shannon diversity indices declined from diagnosis to the end of induction chemotherapy. Patients with fever during induction had a lower baseline microbial diversity and higher Ruminococcus g4 abundance than those without fever. The use of either meropenem or piperacillin/tazobactam during induction was correlated with reduced richness and altered composition of the gut microbiome after induction. The Chao index and beta diversity of stool samples significantly differed before conditioning when compared with those of healthy siblings. During allogeneic hematopoietic stem cell transplantation, both the Chao1 and Shannon diversity indices significantly decreased on day 14 but recovered by day 60. Our study highlights the role of gut microbiome diversity and compositional structure in influencing treatment outcomes in children and AYA with hematologic malignancies, providing the information required to improve the gut microbiome configuration and treatment outcomes.