Impact of Xylitol on Oral Microbiome and Blood Stream Infections in HSCT Recipients

Background: Blood stream infections in patients with central venous catheters may arise from translocation of bacteria through a non-intact mucosa. These infections are known as mucosal barrier injury–laboratory confirmed blood stream infections (MBI-LCBI). Currently there are no proven strategies to prevent bacteremia secondary to mucosal barrier injury after hematopoietic stem cell transplant (HSCT). Xylitol is a non-fermentable sugar alcohol that reduces dental caries, plaque accumulation, and oral disease progression by inhibiting bacterial growth and reducing pathogenic community development. We hypothesized that the addition of Xylitol to standard oral care will decrease bacteremia from oral flora. Methods: We are conducting a prospective randomized study to test our hypothesis. All patients receive standard oral care while half are randomized to also receive daily Xylitol oral wipes. Oral exams are performed at baseline and weekly for the first 28 days post HSCT. Metagenomic shotgun sequencing of gingival samples is performed before and after HSCT. For patients who develop blood stream infection (BSI), whole genome sequencing of pathogenic bacterial isolates is currently being performed in cases and controls, to assess for genetic relatedness to corresponding strains present within the patient's oral microbiome preceding the infection. Results: Preliminary interim analysis of 13 patients demonstrates improved oral health overall (Figure 1). Oral care with Xylitol appeared to prevent Streptococcus mitis/oralis dominance in the oral microbiome (Figure 2). Additionally, the use of Xylitol may prevent BSI from Streptococcus mitis oralis (BSI events n = 0/5) compared to standard oral care (BSI events n = 2/8) within the first 8 days post-transplantation. Interestingly, Streptococcus mitis/oralis comprised 70% of the oral microbiome in one child who subsequently developed a Streptococcus mitis/oralis BSI (Figure 3).Figure 2Relative Streptococcus mitis/oralis abundance in oral microbiome. (A) Standard of care group (SOC) and Xylitol group post-transplant (B) Xylitol group only at baseline and post-transplant and (C) Standard of care group only at baseline and post-transplant.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 3Species abundance represented by bubble chart. (A) Standard of care patient with increase Streptococcus abundance post-transplant (B) Xylitol patient with decrease Streptococcus abundance post-transplant.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The expected study completion date is December 2017. Conclusions: The addition of Xylitol to oral standard care appears to decrease dental plaque, gingivitis and oral ulcerations in patients undergoing HSCT. Xylitol may also impede Streptococcus mitis/oralis dominance in the oral microbiome with potential reduction in blood stream infections.