A Distinct Intestinal Domination Fingerprint in Patients Undergoing Allo-HSCT: Dynamics, Predictors and Implications on Clinical Outcomes

Background: Although Enterococcus domination has been extensively evaluated in the context of allogeneic hematopoietic stem cell transplantation (allo-HSCT), the prevalence and clinical implications of other dominant genera remain poorly understood. Objective: In this study, we sought to determine the dynamics, predictors and clinical implications of intestinal domination in Brazilian patients undergoing allo-HSCT. Methods: In a prospective study of four Brazilian centers, fecal specimens were collected longitudinally from prior to allo-HSCT to six months after. To identify intestinal domination, we performed 16S rRNA gene sequencing using Illumina platform. We then evaluated the impact of intestinal domination on overall survival and acute graft versus host disease (aGvHD) incidence. Finally, to identify predictors of intestinal domination, we performed a logistic regression model. Results: A total of 192 fecal specimens were collected from 69 patients. Among these specimens, 131 (68%) had intestinal domination. The top four dominant genera were Bacteroides, Akkermansia, Phascolarctobacterium, and Escherichia-Shigella. No significant association was identified between intestinal domination by these genera and overall survival and aGvHD incidence. Additionally, we identified that no patient-level characteristic reliably predicts intestinal domination. Conclusion: Our findings suggest that the prognostic significance of intestinal domination may vary according to the dominant genera and to the population being evaluated.