Risk Factors and Outcomes of Vancomycin-Resistant Versus Vancomycin-Sensitive Enterococcal Bloodstream Infections in Patients With Acute Myeloid Leukemia

Abstract

Background Studies have shown increased mortality from vancomycin-resistant enterococcal (VRE) bloodstream infections (BSI) in neutropenic patients. Whether these mortality differences pertain to acute myeloid leukemia (AML) patients is unknown. We compared risk factors and outcomes between VRE and vancomycin-sensitive enterococcal (VSE) BSIs in AML patients. Methods We conducted a single-center, 5-year, retrospective cohort study of AML patients with enterococcal BSI. Neutropenia duration, Enterococcus species, vancomycin exposure, VRE colonization, 7- and 30-day mortality, age, sex, length of stay, and central line status were compared and analyzed. Results There were a total of 77 AML patients with enterococcal BSI, 54.5% had VRE. Enterococcus faecalis and Enterococcus faecium accounted for 28.5% and 62.3% of BSI, respectively. The E. faecalis isolates were more likely to be VSE (91% vs 9%, P < 0.001) and E. faecium isolates to be VRE (71% vs 29%, P < 0.001). Duration of neutropenia was significantly longer (27.3 days vs 2.7 days, P < 0.005) among VRE patients. Recent vancomycin use and VRE colonization were associated with VRE BSI. There were no differences in bacteremia duration, length of stay, or 7- and 30-day mortality between VRE and VSE BSI. Conclusion Enterococcal infections among AML patients are more likely to be caused by vancomycin-resistant E. faecium. The risk is increased by VRE colonization and vancomycin exposure. In a relatively homogenous group of patients, treatment-related factors may affect outcome more than species type or susceptibility of bacterial isolates. This finding is important for future development of patient education, preventive, and treatment protocols.