Clinical and molecular epidemiology of vancomycin-resistant Enterococcus faecium during its emergence in a city in southern Texas

Clin Infect Dis. 1995 Nov;21(5):1234-7. doi: 10.1093/clinids/21.5.1234.


During a 19-month period from April 1993 to October 1994, 41 isolates of vancomycin-resistant Enterococcus faecium (VREF) were detected in seven different hospitals in a city in southern Texas. A case-control study to determine the risk factors for acquisition was done in the hospital in which the majority of isolates were detected. Pulsed-field gel electrophoresis (PFGE) of whole-cell DNA was used to determine strain identity. Thirty-five (85%) of the 41 VREF isolates were of the vanB phenotype. Of these, 32 (91%) of 35 were the same strain by PFGE typing. The same vanB strain was documented in five different hospitals in the city. In contrast, 4 (67%) of 6 of the vanA phenotype VREF isolates were distinct strains by PFGE typing. Significant risk factors for colonization or infection with VREF were prior exposure to antibiotics (P = .04), the previous use of third-generation cephalosporins (P = .03), and the previous use of parenteral vancomycin (P = .002). Infection-control and antibiotic-utilization measures were implemented to control cross-transmission and selection of VREF isolates. During the emergence of VREF in our city, clonal dissemination of a single strain of vanB VREF among six hospitals was documented. Limited cross-transmission of vanA phenotype VREF isolates occurred, but most vanA VREF isolates were distinct strains selected in individual hospital environments.

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Case-Control Studies
  • DNA, Bacterial / genetics
  • Drug Resistance, Microbial / genetics
  • Electrophoresis, Gel, Pulsed-Field
  • Enterococcus faecium / drug effects*
  • Enterococcus faecium / genetics*
  • Enterococcus faecium / isolation & purification
  • Gram-Positive Bacterial Infections / drug therapy
  • Gram-Positive Bacterial Infections / epidemiology*
  • Gram-Positive Bacterial Infections / microbiology
  • Humans
  • Molecular Epidemiology
  • Phenotype
  • Risk Factors
  • Texas / epidemiology
  • Vancomycin / pharmacology*


  • Anti-Bacterial Agents
  • DNA, Bacterial
  • Vancomycin