Cutaneous dysbiosis characterizes the post-allogeneic hematopoietic stem cell transplantation period.

Gut dysbiosis is linked to mortality and the development of graft-versus-host disease after hematopoietic stem cell transplantation (HSCT), but the impact of cutaneous dysbiosis remains unexplored. We performed a pilot observational study, obtained retroauricular and forearm skin swabs from 12 adult patients before conditioning chemotherapy/radiation and at 1 week, 1 month, and 3 months after allogeneic HSCT, and performed shotgun metagenomic sequencing. The cutaneous microbiome among HSCT patients was enriched for gram-negative bacteria such as Escherichia coli and Pseudomonas, fungi, and viruses. Enrichment with bacteriophages and Polyomavirus species was observed among patients who died within 1 year. We observed longitudinal stability of the cutaneous microbiome at the 3-month time point among those who survived beyond 1 year after HSCT, although these may simply be a reflection of the overall medical status of the patients. There was no association with fungal abundance and any of the outcomes observed. The cutaneous microbiome may be a reservoir of pathobionts among allogeneic HSCT patients. Our findings suggest that cutaneous dysbiosis exists after HSCT, but the ultimate implication of this to patient outcomes remains to be seen through larger studies.