Salivary microbiome alterations in HSCT recipients. (A) Principal-coordinates analysis based on weighted UniFrac distance matrix of saliva samples from healthy individuals and HSCT recipients before transplantation and periengraftment. An increase in distance between periengraftment samples and healthy control and between periengraftment samples and pretransplantation samples was observed (false discovery rate [FDR]–corrected P = .0015). (B) Shannon index of healthy controls and pretransplant and periengraftment patients (**FDR-corrected P < .001). (C) Changes in the Shannon index over time for all HSCT patients (n = 184). Day 0 represents the day of the HSCT. (D) Kaplan-Meier estimated overall survival (OS) and progression-free survival (PFS) by pre-engraftment α diversity; high and low diversity are relative to median Shannon index. P value was calculated using the log-rank test.