Incidence and characteristics of early bacterial infection within 100 days after unrelated cord blood transplantation (UCBT) were assessed for 664 pediatric and 1208 adult recipients in Japan. Cumulative incidence of early bacterial infection at day 100 post-UCBTwas 11% (95% confidence interval [CI], 8%-13%) for children and 21% (CI, 19%-24%) for adults (P \.0001). Early bacterial infection in adults had a significant impact on mortality (hazard ratio [HR] 5 2.1, CI, 1.7-2.6; P\.0001), although

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... no significant risk factors were identified. Multivariate analysis identified older age group (6-10, and 11-15 years versus 0-5 years of age) at transplant (HR 5 2.0 and 2.7, CI, 1.1-3.5 and 1.4-4.9; P 5 .020 and .002, respectively) as an independent risk factor of early bacterial infection for children. Early bacterial infection in children did not have a significant impact on mortality when adjusted. Of 315 bacteremia, 74% were caused by Gram-positive microorganisms. Pneumonia occurred in 39 patients including 13 cases of Stenotrophomonas maltophilia pneumonia. Early bacterial infection had a negative effect on survival for adults and the median day of development was 10 days after transplant, suggesting that the prevention of bacterial infection in the very early post-UCBT phase is important.