Bloodstream Infection after Reduced-Intensity Umbilical Cord Blood Transplantation Versus Other Reduced-Intensity Allogeneic Hematopoietic Stem Cell Transplantation.

Blood stream infection (BSI) is a major cause of transplant-related mortality (TRM) following allogeneic hematopoietic stem cell transplantation, and to overcome it, reduced-intensity preparative regimens were developed in recent years. However, little information has been reported on BSI after reduced-intensity cord blood transplantation (RI-CBT). To clarify the characteristics of BSI after RI-CBT, we compared the incidence of microbiologically documented BSI before day 100 between RI-CBT and reduced-intensity non-cord blood allogeneic hematopoietic stem cell transplant (RI-non-CBT) recipients in Toranomon hospital, Japan. RI-non-CBT group includes related bone marrow (rBM), related peripheral blood stem cell (rPBSC) and unrelated bone marrow (uBM) transplantation. We retrospectively reviewed the first events of BSI in 211 consecutive adult patients between Jan 2004 and July 2006. One hundred and fifteen patients received RI-CBT and 96 patients received RI-non-CBT (4 from rBM, 34 from rPBSC and 58 from uBM). The median ages of patients in both groups were 55 years. All of the preparative regimens were fludarabine-based and prophylaxis against GVHD was tacrolimus alone in most of the RI-CBT recipients and combination of calcinurin inhibitor and short-term methotrexate in most of the RI-non-CBT recipients. The median time to achieve neutrophil engraftment was delayed in RI-CBT group (day 20 vs. day15). The cumulative incidence of engraftment at day 60 was 73.0% in RI-CBT group versus 90.6% in RI-non-CBT group. The cumulative incidence of BSI was 39.3% at day 100 and RI-CBT group tended to have more BSI compared to RI-non-CBT group (46.1% vs. 31.3%, p=0.0122), particularly at the early points after transplantation. Median day of positive culture for bacteremia was earlier (day 9 vs. day 14) in RI-CBT group. In spite of reduced-intensity preparative regimen, RI-CBT in adults is associated with higher rates of BSI at early time points after transplantation.