Safety of Probiotics Among High-Risk Pediatric Hematopoietic Stem Cell Transplant Recipients

Introduction: Increased diversity of the intestinal microbiome has been significantly associated with lower mortality after hematopoietic stem cell transplant (HSCT). Probiotics, such as Lactobacillus species with defined probiotic potential, may have beneficial properties including restoration of commensal species to the intestinal tract, anti-microbial effects, and healing of the intestinal mucosa. However, the use of probiotics in immune-compromised patients raises concerns, specifically regarding the risk for possible Lactobacillus bacteremia. Risk of bacteremia is an even greater concern in HSCT patients with breakdown of mucosal barriers, specifically patients with Clostridium difficile infection (CDI) or gastrointestinal graft-versus-host disease (GVHD). Minimal data have been reported on the safety of probiotics in these high-risk HSCT populations. Methods: We performed a retrospective study of allogeneic HSCT recipients at our institution between 2011 and 2016, and identified 14 patients (median age 7 years) prescribed probiotics, 10 of whom received probiotics prior to day 100 after HSCT. Results: Eight of ten patients were diagnosed with acute GVHD, four of whom (40%) specifically had acute GVHD involving the gastrointestinal tract. Five patients (50%) on probiotics prior to day 100 were diagnosed with CDI (median onset at day 13 post-transplant). There were no cases of Lactobacillus bacteremia, including in patients with GVHD or CDI. Conclusion: This small case series supports the safe use of probiotics in a high-risk population of pediatric HSCT patients with compromised intestinal mucosal integrity. Further studies are needed to determine if probiotics have benefit in preventing and treating gastrointestinal GVHD or CDI.