ALBERT

Description: Introduction: The impact of commensal bacteria harbored in the gastrointestinal tract known as the microbiota has long been recognized as a pivotal factor in allogeneic hematopoietic stem cell transplantation (aHSCT). The microbiota is at the origin of acute graft-versus-host disease (aGVHD) and infections, two important lethal complications in aHSCT. High-dose conditioning chemotherapy prior aHSCT disrupts the gut epithelial barrier allowing bacterial by-products to translocate into the peripheral blood and modulates T cell response and pro-inflammatory cytokines. Such observation led to an effort by certain transplant centers to eliminate bacterial colonization prior to aHSCT to decrease the risk of gram-negative bacterial translocation. In this study, we assessed whether patients' gut decontamination prior to allogeneic stem cell infusion influenced the frequency of aGVHD, pneumomatosis coli (PC) a significant complication of gastrointestinal (GI) GVHD and overall survival. Methods: We retrospectively reviewed the charts of 543 patients who had undergone a single myeloablative or nonmyeloabaltive aHSCT for hematological malignancies from two academic hospitals in the province of Quebec, Canada between January 2005 and December 2012. Exclusion criteria included prior aHSCT, syngeneic and haploidentical aHSCT. Each university hospital has implemented a different pre-transplant antibioprophylaxis guideline. At HMR hospital, ciprofloxacin or moxifloxacine were started at initiation of the conditioning regimen for gut decontamination, but were omitted in patients with fluoroquinolone or penicillin allergy and during nosocomial infections outbreak. On the other hand, in the CHU de Quebec patients were not prescribed prophylactic antibiotics (ATB). In addition, ATB used to treat infections before the stem cells infusion were considered. To determine the impact of ATB, we performed multivariable analyses adjusting for the following confounding factors: age, gender, stem cell origin (source), donor type/match, and conditioning regimens to compare the frequency of aGVHD, PC, leucocytes recovery at day+14 and overall survival (OS) in patients receiving or not ATB. Results: 500 patients were included and a total of 240 (48%) patients received ATB at the time of conditioning regimen. Demographics were similar in both groups with mean age of 48 years. Frequency of grade II-IV aGVHD was more elevated in patients receiving ATB compared to the no ATB group (42% vs 28% respectively with adjusted OR (aOR)=1.53 (p