From aseptic ideal to microbial community balance: The shift in gut microbiota management models for hematopoietic stem cell transplant patients.

In the clinical practice of hematopoietic stem cell transplantation (HSCT), we find ourselves in a thought-provoking paradox. On one hand, hematologists strive to create an sterility paradigm for patients through systemic drug baths before admission, prophylactic use of broad-spectrum antibiotics during the conditioning phase, and sterile diets during transplantation. The core goal of these strategies is to minimize the risk of infection for patients. However, from a microbiological perspective, a completely different picture emerges; the gut microbiota is a virtual organ that co-evolved with the host and possesses critical metabolic and immune regulatory functions. Microbiologists point out that indiscriminate antibiotic clearing strategies, while attempting to eradicate a few pathogens, also destroy the diversity and ecological functions of the microbiota necessary for maintaining gut homeostasis, leading to the collapse of intestinal barrier, disruption of intestinal epithelial energy metabolism, and loss of immune regulatory signals. Increasing evidence suggests that this pursuit of aseptic ideal, particularly the extensive suppression of the gut microbiome by broad-spectrum antibiotics, may be opening another Pandora's box: severe gut dysbiosis, which is not only associated with unexplained fever and diarrhea but may also affect the overall reconstruction and regulation of the patient's immune system, thus correlating with the occurrence and development of challenging complications such as graft-versus-host disease (GVHD). The divergence of views between hematologists and microbiologists highlights a core cognitive conflict in contemporary HSCT management: are we treating a patient, or are we regulating a superorganism composed of human cells and symbiotic microorganisms? This comment aims to analyze this contradiction based on existing evidence and advocate for a more refined and ecologically-oriented new model of clinical management.