Risk factors for enterococcal bacteremia in allogeneic hematopoietic stem cell transplant recipients

Bacteremia is a well known cause of morbidity and mortality in hematopoietic stem cell transplant (HSCT) recipients and enterococci are among the most frequently isolated pathogens. The aim of this study was to identify risk factors for enterococcal bacteremia during the first 30 days after allogeneic HSCT. A retrospective case-control study was performed; for each case, 3 controls were randomly selected among 306 patients transplanted during the study period (January 1, 2004 to December 31, 2007). Odds ratios (OR) with 95% confidence intervals (CI) were calculated for variables influencing the risk for bacteremia. Overall, 33 patients developed enterococcal bacteremia, within a median of 9 days after HSCT (range, 2-24). The cumulative incidence was 10.8%. Multivariate analysis identified the following variables as risk factors for enterococcal bacteremia: donor and transplant type (greater risk for mismatched related or cord blood) (OR=8.98, 95% CI, 1.65-48.99 and OR=7.52, 95% CI, 1.56-36.31, respectively, P=0.047); severe (grades 3-4) mucositis (OR=9.04, 95% CI, 1.97-41.52, P=0.018); pharyngeal enterococcal colonization (OR=4.48, 95% CI, 1.11-18.03, P=0.035); and previous empirical therapy with cephalosporins (OR=4.16, 95% CI, 0.93-18.66 for 1-7 days of therapy, and OR=7.31, 95% CI, 1.78-30.12 for 8-23 days, P=0.018). Higher Karnofsky score (≥50) and previous empirical therapy with glycopeptides were associated with a decreased risk (OR=0.25, 95% CI, 0.06-0.97, P=0.045 and OR=0.11, 95% CI, 0.02-0.59, P=0.010, respectively). The crude mortality at 7 and 30 days was 12% (4/33) and 24% (8/33), respectively. Enterococcal bacteremia is frequent after allogeneic HSCT. The factors associated with this infection are type of transplant, pharyngeal colonization, severe mucositis, and use of cephalosporins. Good general conditions and the use of vancomycin were associated with lower risk of enterococcal bacteremia.