Omitting Ciprofloxacin Prophylaxis in Patients Undergoing Allogeneic Hematopoietic Stem Cell Transplantation and Its Impact on Clinical Outcomes and Microbiome Structure

Fluoroquinolone prophylaxis during allogeneic hematopoietic stem cell transplantation (allo-HSCT) reduces bloodstream infections. However, this practice affects the gut microbiome and potentially increases dysbiosis, which is closely related to transplantation outcomes, and lower gastrointestinal (GI) tract acute graft-versus-host disease (GVHD). This study assessed the impact of omitting ciprofloxacin prophylaxis on GI GVHD, clinical outcomes, and microbiome composition in patients undergoing allo-HSCT. In this single-center, retrospective study comprising recipients of allo-HSCT performed between 2018 and 2020, routine ciprofloxacin prophylaxis (the exposure variable) was stopped in December 2018. The primary outcome was acute lower GI GVHD within 100 days post-transplantation; secondary outcomes were 1-year overall survival, nonrelapse mortality, relapse, and overall acute GVHD. Outcomes were compared using univariate and multivariate analyses and Kaplan-Meier/competing-risk analyses. Sequential stool samples were collected prospectively from a subpopulation of recipients, and the microbiome composition was analyzed. Seventy-five of the 129 patients (58.1%) received prophylactic ciprofloxacin treatment. Baseline characteristics did not differ between the 2 study groups: patients with ciprofloxacin prophylaxis and those without ciprofloxacin prophylaxis. The rate of lower GI GVHD also did not differ between the 2 groups (24% versus 18.5%; P = .597). None of the secondary outcomes was significantly different between the 2 groups in univariate, multivariate, and time-to-event analyses. In addition, microbiome analysis in a subpopulation of 22 patients did not reveal any significant between-group difference in alpha or beta diversity. Omitting prophylactic ciprofloxacin during allo-HSCT did not affect microbiome composition, lower GI-GVHD rate, or other significant clinical outcomes. The use of prophylactic antibiotics in this setting should be evaluated further. (C) 2021 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.