Vancomycin-resistant Enterococcus faecium infection in patients with hematologic malignancy:: patients with acute myeloid leukemia are at high-risk

Background: Vancomycin-resistant enterococci (VRE) are significant nosocomial pathogens in patients with hematologic malignancy. Identification of risk factors for infection is necessary for targeted prevention and surveillance. Objectives and Methods: An outbreak of VRE infection occurred at a tertiary cancer hospital between 1 August 2003 and 30 June 2005. Infection control measures recommended by the Society for Healthcare Epidemiology of America were used throughout the outbreak period. A matched case-control study was performed to identify risk factors for VRE infection. Results: Fourteen VRE infections (13 episodes of bacteremia, one urinary tract infection) occurred a median of 10.5 d following hospital admission. All were due to Enterococcus faecium vanB. Univariate analysis identified the following variables to be significantly associated with VRE infection: presence of neutropenia, neutropenia >= 7 d, underlying diagnosis of acute myeloid leukemia (AML), and receipt of vancomycin, metronidazole or carbapenem antibiotic therapy in the 30 d prior to infection. On multivariate analysis, an underlying diagnosis of AML [odds ratio (OR), 15.00; P = 0.017] and vancomycin therapy during the previous 30 d (OR, 17.96; P = 0.036) were retained as independent risk factors for infection. Conclusions: Risk stratification for development of VRE infection is possible for patients with hematologic malignancy. Patients with AML represent a high-risk population, and targeted prevention strategies must include improved antibiotic stewardship, particularly judicious use of vancomycin therapy.