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Heterogeneity of vat(E)-carrying plasmids in Enterococcus faecium recovered from human and animal sources

Shabbir Simjee1, Yifan Zhang, Patrick F McDermott

  • 1Division of Animal and Food Microbiology, Office of Research, Center for Veterinary Medicine, U.S. Food and Drug Administration, Laurel, MD, USA.

International Journal of Antimicrobial Agents
|August 17, 2006
PubMed

Insights

Quinupristin/dalfopristin resistance in Enterococcus faecium is linked to the vat(E) gene. This resistance gene was found on various plasmids in both farm and human isolates, suggesting potential transmission.

Area of Science:

  • Microbiology
  • Antimicrobial Resistance
  • Molecular Biology

Background:

  • Enterococcus faecium is a significant opportunistic pathogen.
  • Quinupristin/dalfopristin (Q/D) resistance is an emerging concern in E. faecium.
  • The vat(E) gene is implicated in Q/D resistance.

Purpose of the Study:

  • To investigate the genetic basis of Q/D resistance in E. faecium isolates from poultry farms and a human source.
  • To characterize the genetic relatedness and plasmid carriage of the vat(E) gene in these isolates.

Main Methods:

  • Polymerase chain reaction (PCR) for vat(E) detection.
  • Pulsed-field gel electrophoresis (PFGE) for strain typing.
  • Southern hybridization for plasmid analysis.

Main Results:

  • All analyzed E. faecium isolates (33 farm, 1 human) harbored the vat(E) gene.
  • PFGE revealed 14 distinct patterns, distinguishing the human isolate from farm isolates.
  • The vat(E) gene was located on an 11 kb plasmid, with five distinct plasmid hybridization types identified.
  • The human isolate's vat(E)-carrying plasmid showed high similarity to a farm isolate's plasmid.

Conclusions:

  • The vat(E) gene, conferring Q/D resistance, is carried on diverse plasmids within a heterogeneous E. faecium population.
  • Genetic similarities between plasmids from farm and human isolates suggest potential for transmission and acquisition by human-pathogenic E. faecium.

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