title: Conjugative transfer of the virulence gene, esp, among isolates of Enterococcus faecium and Enterococcus faecalis.
abstract: OBJECTIVE
  The enterococcal surface protein gene, esp, is a major putative pathogenicity marker in clinical isolates of Enterococcus faecium and Enterococcus faecalis. This study demonstrates in vitro conjugative transfer of the esp gene among E. faecium and E. faecalis.
  
  
  METHODS
  Enterococcal isolates from clinical samples, positive for esp, were mated on filters with enterococcal recipients. Transconjugants were checked for transfer of antibiotic resistance determinants and co-mobilization of the esp gene. They were also characterized by PCR and plasmid profiling/PFGE typing including Southern hybridizations with labelled esp probes. Transfer as triggered by excision was tested using Taqman PCR.
  
  
  RESULTS
  Two of five E. faecalis and five of nine E. faecium transferred antibiotic resistance determinants into a recipient. Of the transconjugants analysed by PCR for acquisition of esp, only isolates from two E. faecalis and a single E. faecium mating were positive. In the donor strains, the esp gene was located on the chromosome. Molecular analysis revealed a plasmid localization of esp in the E. faecium transconjugant and chromosome-to-chromosome transfer in E. faecalis.
  
  
  CONCLUSIONS
  The esp gene is transferable by conjugation among enterococcal isolates.
authors.affiliation: Robert Koch Institute, Wernigerode Branch, Burgstr. 37, 38855 Wernigerode, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Oancea
authors.forename: Ingo
authors.initials: I
authors.lastname: Klare
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Witte
authors.forename: Guido
authors.initials: G
authors.lastname: Werner
mesh_terms: D003227:Conjugation, Genetic / Q000235:genetics*; D017931:DNA Primers; D004269:DNA, Bacterial / Q000235:genetics; D013293:Enterococcus faecalis / Q000187:drug effects / Q000235:genetics*; D016984:Enterococcus faecium / Q000187:drug effects / Q000235:genetics*; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D006801:Humans; D010957:Plasmids / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial; D037521:Virulence Factors