Infectious complications following allogeneic HLA-identical sibling transplantation with antithymocyte globulin-based reduced intensity preparative regimen

In the setting of reduced-intensity conditioning (RIC) regimens for allogeneic stem cell transplantation (allo-SCT), the epidemiology of transplant-related infections is still poorly defined. In 101 high-risk patients who received an HLA-identical sibling allo-SCT after RIC, including fludarabine, busulfan and antithymocyte globulin (ATG), we report during the first 6 months a cumulative incidence of positive CMV antigenemia of 42% (95% CI 32-52%), developing at a median of 37 (range 7-116) days without evidence of CMV disease (median follow-up, 434 days). The cumulative incidence of bacteremia was 25% (95% CI 17-33%), occurring at a median of 67 (range 7-172) days, while patients had recovered a full neutrophil count. In all, 65% of the bacteremia (95% CI 49-81%) were gram negative. The cumulative incidence of fungal infections was 8% (95% CI 3-13%), with a median onset of 89 (range 7-170) days. In multivariate analysis, stem cell source (bone marrow; P = 0.0002) was significantly associated with the risk of positive CMV antigenemia, while higher doses of prednisone (> 2 mg/kg) represented the major risk factor for bacteremia (P = 0.0001). Infectious-related mortality was 5% (95% CI 1-9%), with aspergillosis being the principal cause. Collectively, these results suggest that prospective efforts are warranted to develop optimal antimicrobial preventive strategies after RIC allo-SCT.