title: Molecular epidemiology of vancomycin-resistant enterococci: a 2-year perspective.
abstract: OBJECTIVE
  To determine the molecular epidemiology of vancomycin-resistant enterococci (VRE) at our medical center in order to identify the extent of strain clonality and possible transmission patterns of this pathogen.
  
  
  METHODS
  An important facet of our infection control program includes molecular typing of all clinical and surveillance isolates of VRE to determine transmission patterns in the hospital. Molecular strain typing is performed by restriction endonuclease analysis (REA) of genomic DNA. REA patterns are visually compared to categorize VRE strains into type and subtype designations.
  
  
  METHODS
  A 588-bed, university-affiliated, tertiary-care hospital and a neighboring 155-bed rehabilitation facility.
  
  
  RESULTS
  From January 1995 through December 1996, 379 VRE isolates were collected from 197 patients. Thirty-three genotypes were determined by REA typing; 15 genotypes were implicated in 29 instances of potential nosocomial transmission. Three major clusters of VRE involving patients on multiple nursing units and two adjacent hospitals were identified. The remaining instances of nosocomial transmission occurred in small patient clusters.
  
  
  CONCLUSIONS
  In conclusion, the VRE epidemic at this medical center is polyclonal. VRE transmission patterns are complex, and, while large clusters do occur, the usual pattern of nosocomial acquisition of this pathogen occurs in the setting of "mini-clusters".
authors.affiliation: Department of Pathology, Northwestern University Medical School, Chicago, Illinois 60611, USA.
authors.forename: V
authors.initials: V
authors.lastname: Stosor
authors.forename: J
authors.initials: J
authors.lastname: Kruszynski
authors.forename: T
authors.initials: T
authors.lastname: Suriano
authors.forename: G A
authors.initials: GA
authors.lastname: Noskin
authors.forename: L R
authors.initials: LR
authors.lastname: Peterson
mesh_terms: D015373:Bacterial Typing Techniques; D002641:Chicago / Q000453:epidemiology; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D004196:Disease Outbreaks; D016983:Enterococcus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D016908:Gram-Positive Bacterial Infections / Q000453:epidemiology / Q000635:transmission; D006801:Humans; D017720:Molecular Epidemiology; D011159:Population Surveillance; D000091402:Prohibitins; D013029:Space-Time Clustering; D020713:Vancomycin Resistance