The Microbiome and Hematopoietic Cell Transplantation: Past, Present, and Future

The human microbiome is comprised of the bacteria, archaea, viruses, fungi, and other microeukaryotes that live on and within the human host. Alterations in the microbiome are associated with adverse transplant outcomes including the expected infectious complications following allogeneic hematopoietic cell transplantation (allo-HCT) in addition to diseases that are not classically microbe associated. For example, recent data suggest an association between certain microbial community structures and mortality, disease relapse, risk of infection, and graft-versus-host disease (GVHD) [1-3].