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Genetic diversity of Tn1546-like elements in clinical isolates of vancomycin-resistant enterococci

Kidon Sung1, Saeed A Khan, Mohamed S Nawaz

  • 1Division of Microbiology, National Center for Toxicological Research/FDA, 3900 NCTR Road, Jefferson, AR 72079, USA.

International Journal of Antimicrobial Agents
|May 9, 2008
PubMed

Insights

Genetic diversity of Tn1546 in vancomycin-resistant Enterococcus faecium (VRE) was investigated. Unique structural arrangements of vanA elements were identified, including IS1251 insertion and plasmid translocation, revealing novel genetic diversity.

Area of Science:

  • Microbiology
  • Genetics
  • Molecular Biology

Background:

  • Vancomycin-resistant enterococci (VRE) are a significant public health concern.
  • The Tn1546 transposon is responsible for vancomycin resistance in enterococci.
  • Understanding the genetic diversity of Tn1546 is crucial for controlling VRE spread.

Purpose of the Study:

  • To investigate the genetic diversity of the Tn1546 transposon in 17 vancomycin-resistant Enterococcus faecium isolates.
  • To characterize the structural variations and genetic elements associated with vancomycin resistance.

Main Methods:

  • Polymerase chain reaction (PCR) amplification of Tn1546 elements.
  • Plasmid DNA extraction and analysis.
  • DNA sequencing of vanSH amplicons.

Main Results:

  • The vanA resistance gene was found on both plasmid and chromosomal DNA in most VRE isolates.
  • Sequence analysis revealed IS1251 insertion between vanS and vanH genes in some isolates.
  • A unique structural arrangement of vanA elements was observed in one isolate due to Tn1546 translocation to a pRUM-like plasmid.

Conclusions:

  • Significant genetic diversity exists within the Tn1546 transposon among VRE isolates.
  • Novel genetic arrangements, including IS1251 insertion and plasmid translocation, contribute to this diversity.
  • These findings enhance our understanding of the evolution and dissemination of vancomycin resistance mechanisms.

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