Changes in Vitamin D and Gut Microbiota in Pediatric Hematopoietic Stem Cell Transplantation Patients with Bloodstream Infections.

Abstract

Background: Vitamin D (VD) and gut microbiota (GM) are important variables in pediatric hematopoietic stem cell transplantation (HSCT) recipients with bloodstream infections (BSI). Both VD and GM play significant roles in immune regulation and in maintaining intestinal barrier function.

Methods: This prospective case-control study included 48 consecutive pediatric patients who underwent HSCT, as well as 20 healthy children from the community. Plasma samples were collected pre- and post-HSCT, together with post-HSCT fecal samples. Serum 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D3 (1,25(OH)₂D₃) were measured using chemiluminescence and enzyme linked immunosorbent assay, respectively. GM was analyzed by 16S rDNA next generation sequencing.

Results: The incidence of BSI in pediatric HSCT recipients was 33.3% (16/48). No significant differences in serum 25(OH)D or 1,25(OH)₂D₃ levels were observed between the BSI and non-BSI groups either before or after transplantation, or with the healthy control group. The α-diversity of GM in BSI and non-BSI patients was significantly lower than in healthy subjects. Proteobacteria were significantly more abundant in BSI patients than in non-BSI patients (p = 0.0434) or healthy controls (p = 0.0193). Pediatric HSCT patients showed significantly higher levels of Staphylococcus (p < 0.001), Pseudomonas (p < 0.001), Enterococcus (p < 0.001), Clostridium innocuum (p = 0.0175) and Enterobacter (p = 0.0394) compared to the controls, whereas the levels of Firmicutes (p = 0.009), Actinobacteria (p < 0.001), Bifidobacterium (p < 0.001) and Faecalibacterium (p < 0.001) were significantly lower. β-diversity analysis revealed significant population differences between the three groups.

Conclusions: These results indicate there is no practical value in monitoring VD in HSCT patients. During HSCT and BSI, the GM experiences a loss of probiotics and an increase in potential pathogens.