Clinical and molecular characterization of vancomycin-resistant Enterococcus faecium strains during establishment of endemicity

Clin Infect Dis. 2001 Aug 15;33(4):511-6. doi: 10.1086/322615. Epub 2001 Jul 11.


To characterize the molecular epidemiology of vancomycin-resistant Enterococcus faecium (VREF) in Tennessee, VREF isolates that were recovered from patients during a 3-year period at a tertiary care center and throughout the state were typed by means of pulsed-field gel electrophoresis. Clinical characteristics and outcomes of patients colonized or infected with different strain types were also examined. A total of 34 different strain types were identified. A single VREF strain (type O) predominated (63 [61%] of 103 single-patient isolates (i.e., 1 isolate per patient) obtained from 7 different health care institutions). There were no significant differences between patients harboring type O strains and those harboring non-type O strains (P> or =.05). The rate of recovery of type O subtypes and strains other than type O increased over the 3-year study period. Establishment of VREF endemicity was initially characterized by clonal spread of type O strains. Subsequently, polyclonal dissemination may have been due to microevolutionary changes among type O strains.

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacterial Typing Techniques
  • Cluster Analysis
  • Electrophoresis, Gel, Pulsed-Field
  • Endemic Diseases*
  • Enterococcus faecium / classification*
  • Enterococcus faecium / drug effects*
  • Enterococcus faecium / genetics
  • Enterococcus faecium / isolation & purification
  • Female
  • Gram-Positive Bacterial Infections / epidemiology*
  • Gram-Positive Bacterial Infections / microbiology
  • Gram-Positive Bacterial Infections / physiopathology
  • Humans
  • Male
  • Middle Aged
  • Polymerase Chain Reaction
  • Tennessee / epidemiology
  • Vancomycin / pharmacology
  • Vancomycin Resistance / genetics*


  • Anti-Bacterial Agents
  • Vancomycin