A polyclonal outbreak of bloodstream infections by Enterococcus faecium in patients with hematologic malignancies

Am J Infect Control. 2017 Mar 1;45(3):260-266. doi: 10.1016/j.ajic.2016.10.002. Epub 2016 Nov 14.

Abstract

Background: Enterococcus faecium causes bloodstream infection (BSI) in patients with hematologic malignancies (HMs). We studied the clinical features and outcomes of patients with HM with vancomycin-sensitive E faecium (VSE) and vancomycin-resistant E faecium (VRE) BSI and determined the genetic relatedness of isolates and circumstances associated with the upsurge of E faecium BSI.

Methods: Case-control study of patients with HM and E faecium-positive blood culture from January 2008-December 2012; cases were patients with VRE and controls were VSE isolates. The strains were tested for Van genes by polymerase chain reaction amplification and we performed pulsed-field gel electrophoresis to determine genetic relatedness.

Results: Fifty-eight episodes of E faecium BSI occurred: 35 sensitive and 23 resistant to vancomycin. Mortality was 46% and 57%, attributable 17% and 40%, respectively. Early stage HM was associated with VSE (P = .044), whereas an episode of BSI within the 3 months before the event (P = .039), prophylactic antibiotics (P = .013), and vancomycin therapy during the previous 3 months (P = .001) was associated with VRE. The VanA gene was identified in 97% of isolates studied. E faecium isolates were not clonal.

Conclusions: E faecium BSI was associated with high mortality. This outbreak of VRE was not clonal; it was associated with antibiotic-use pressure and highly myelosuppressive chemotherapy.

Keywords: Molecular epidemiology; Mucosal barrier injury; Vancomycin-resistant Enterococcus faecium.

MeSH terms

  • Adolescent
  • Adult
  • Case-Control Studies
  • DNA, Bacterial / genetics
  • Disease Outbreaks*
  • Electrophoresis, Gel, Pulsed-Field
  • Enterococcus faecium / classification
  • Enterococcus faecium / genetics
  • Enterococcus faecium / isolation & purification*
  • Female
  • Genetic Variation
  • Genotype
  • Gram-Positive Bacterial Infections / epidemiology*
  • Gram-Positive Bacterial Infections / microbiology
  • Hematologic Neoplasms / complications*
  • Humans
  • Male
  • Middle Aged
  • Molecular Epidemiology
  • Molecular Typing
  • Polymerase Chain Reaction
  • Retrospective Studies
  • Sepsis / epidemiology*
  • Sepsis / microbiology
  • Survival Analysis
  • Vancomycin-Resistant Enterococci / classification
  • Vancomycin-Resistant Enterococci / genetics
  • Vancomycin-Resistant Enterococci / isolation & purification*
  • Young Adult

Substances

  • DNA, Bacterial