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Characterization of a highly glycopeptide-resistant Enterococcus gallinarum isolate
1Department of Pathology, Tri-Service General Hospital, Taipei, Taiwan.
Summary
This study identified the vanA gene on a transferable plasmid in vancomycin-resistant Enterococcus gallinarum TSGH63. This finding highlights the need for strict vancomycin use to prevent the spread of antibiotic resistance.
Area of Science:
- Microbiology
- Genetics
- Infectious Diseases
Background:
- Vancomycin-resistant Enterococcus (VRE) infections pose a significant clinical challenge.
- Enterococcus gallinarum TSGH63 exhibits unusual high-level vancomycin resistance.
- Understanding the genetic basis of this resistance is crucial for effective treatment.
Purpose of the Study:
- To investigate the genetic determinant responsible for the unique vancomycin resistance in Enterococcus gallinarum TSGH63.
- To characterize the genetic element conferring high-level vancomycin resistance.
- To assess the transferability of the resistance determinant.
Main Methods:
- Genomic DNA extraction and analysis by pulse-field gel electrophoresis.
- Multiplex polymerase chain reaction (PCR) using primers for vanA, vanB, vanC1, and vanC2/C3 genes.
- Southern blot hybridization with a digoxigenin (DIG)-labeled vanA gene probe.
- In vitro conjugation experiments to assess interspecies gene transfer.
Main Results:
- A 50-kb plasmid was identified in E. gallinarum TSGH63.
- The bacterium was found to harbor both vanA and vanC1 genes.
- The vanA gene, located on the plasmid, was transferable to Enterococcus faecalis JH2-2 via conjugation.
Conclusions:
- This study reports the first isolation of vancomycin-resistant Enterococcus gallinarum with high-level glycopeptide resistance in Taiwan.
- The plasmid-mediated transfer of the vanA gene demonstrates a mechanism for the spread of vancomycin resistance.
- Stringent control over vancomycin usage is essential to mitigate the dissemination of antibiotic resistance.