title: Driving forces of vancomycin-resistant E. faecium and E. faecalis blood-stream infections in children.
abstract: BACKGROUND
  Rates of invasive vancomycin-resistant Enterococcus (VRE) in the USA remains on the rise. Efforts to control vancomycin use and nosocomial transmission have had limited success in halting the spread of this pathogen. The role of antibiotic exposure remains a topic of controversy. We evaluated the association between emergence of VRE-blood-stream infections (BSI), aggregate and individual-patient vancomycin- exposure, and clonal transmission of VRE at an academic pediatric tertiary care hospital.
  
  
  METHODS
  E. faecium and E. faecalis isolates recovered from blood specimens from hospitalized children from 2003-2010 were retrieved from the microbiology database. Aggregate vancomycin use and individual-patient vancomycin exposure 6 months preceding each event of bacteremia were recorded. Pulse-field electrophoresis was performed on selected VRE isolates.
  
  
  RESULTS
  Of 151 episodes of E. faecium and E. faecalis BSI among hospitalized children <18 years of age, 9% (14) were due to VRE. Of these, 5 (36%) were due to nosocomial transmission. Aggregate (r .19, P = 0.3) and individual-patient vancomycin-exposure (X (2)  = .26; P = .87) were not associated with VRE-BSI. On bivariate analysis, OR for developing VRE-BSI among patients infected with clonal isolates was 36 (P < .0001). Infection control interventions, rather than antimicrobial stewardship interventions to decrease vancomycin use, proved to be effective in reducing the rates of VRE-BSI.
  
  
  CONCLUSIONS
  In our experience, VRE-BSI was associated with nosocomial transmission and was independent of aggregate and individual-patient vancomycin-exposure. Molecular epidemiology is a crucial tool to differentiate the role of nosocomial transmission and antibiotic exposure in the emergence of invasive VRE infections among hospitalized children.
authors.affiliation: Infectious Diseases Division, Department of Pediatrics, Vanderbilt University, D-7235 Medical Center North, 1161 21st Avenue South, Nashville, Tennessee, USA.
authors.forename: Maria Cecilia
authors.initials: MC
authors.lastname: Di Pentima
authors.affiliation: Department of Pediatrics, Alfred I. duPont Hospital for Children, Wilmington, Delaware, USA.
authors.forename: Shannon
authors.initials: S
authors.lastname: Chan
authors.affiliation: Christiana Health Care System, Newark, USA.
authors.forename: Carol
authors.initials: C
authors.lastname: Briody
authors.affiliation: Christiana Health Care System, Newark, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Power
authors.affiliation: Nemours Biomedical Research, Wilmington, Delaware, USA.|Department of Food and Resource Economics, University of Delaware, Newark, Delaware, USA.
authors.forename: Jobayer
authors.initials: J
authors.lastname: Hossain
keywords: Bacteremia; Enterococcus faecalis; Enterococcus faecium; Enterococcus spp; Vancomycin