Highly conjugative pMG1-like plasmids carrying Tn1546-like transposons that encode vancomycin resistance in
Haruyoshi Tomita1, Koichi Tanimoto, Satoshi Hayakawa
1Department of Bacteriology and Bacterial Infection Control, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan.
Journal of Bacteriology
|November 18, 2003
Abstract:
A total of 12 VanA-type vancomycin-resistant enterococci, consisting of 10 Enterococcus faecium isolates and two Enterococcus avium isolates, were examined in detail. The vancomycin resistance conjugative plasmids pHTalpha (65.9 kbp), pHTbeta (63.7 kbp), and pHTgamma (66.5 kbp) were isolated from each of three different E. faecium strains. The plasmids transferred highly efficiently between enterococcus strains during broth mating and were homologous with pMG1 (Gm(r); 65.1 kb).
Insights
This study details 12 VanA-type vancomycin-resistant enterococci, including Enterococcus faecium and Enterococcus avium. Researchers identified and characterized three conjugative plasmids responsible for vancomycin resistance transfer between enterococci strains.
Area of Science:
- Microbiology
- Molecular Biology
- Antimicrobial Resistance
Background:
- Vancomycin-resistant enterococci (VRE) pose a significant threat in healthcare settings.
- The VanA type is a common mechanism conferring high-level vancomycin resistance.
- Understanding the genetic elements mediating VRE spread is crucial for infection control.
Purpose of the Study:
- To characterize VanA-type vancomycin-resistant enterococci isolates.
- To identify and analyze the conjugative plasmids responsible for vancomycin resistance.
- To investigate the transfer efficiency and genetic relatedness of these plasmids.
Main Methods:
- Isolation and identification of vancomycin-resistant enterococci.
- Plasmid DNA isolation and characterization (size, type).
- Conjugation experiments to assess transfer efficiency between enterococcal strains.
- Plasmid homology analysis.
Main Results:
- Twelve VanA-type VRE isolates were analyzed (10 E. faecium, 2 E. avium).
- Three conjugative plasmids (pHTalpha, pHTbeta, pHTgamma) were isolated from E. faecium strains.
- These plasmids demonstrated high-efficiency transfer during broth mating and showed homology to pMG1.
Conclusions:
- The identified plasmids are key mobile genetic elements mediating vancomycin resistance spread in enterococci.
- Efficient plasmid transfer highlights the potential for rapid dissemination of VRE.
- Homology to pMG1 suggests a common origin or shared genetic features among resistance plasmids.
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