Related Experiment Video
Updated: Sep 7, 2026
A 1.5 Hour Procedure for Identification of Enterococcus Species Directly from Blood Cultures
Published on: February 10, 2011
Comparison of high-level gentamicin-resistant Enterococcus faecium isolates from different continents
N Woodford1, D Morrison, B Cookson
1Antibiotic Laboratory, Central Public Health Laboratory, London, England.
Abstract:
Eight clinical isolates of Enterococcus faecium highly resistant to gentamicin (MIC, > 1,000 mg/liter) from patients in six hospitals on three continents were investigated for evidence of spread of either a clone of high-level gentamicin-resistant (HLGR) E. faecium or wide dissemination of a gentamicin resistance (Gmr) plasmid. A combination of ribotypes, plasmid profiles, and extended antimicrobial susceptibilities enabled us to distinguish all but two of the isolates and did not suggest clonal dissemination of a single strain. Two isolates from hospitals situated close together appeared identical by these methods. All of the isolates carried Gmr plasmids which appeared to be closely related following digestion with restriction endonucleases. Cross-hybridization studies confirmed extensive DNA homology between these plasmids. The fragments of these plasmids which hybridized with a probe specific for the aac6'aph2" resistance gene did not resemble those seen in the Gmr transposon Tn5281, which was characterized previously in E. faecalis HH22. This study suggests that there has been widespread dissemination of a single Gmr plasmid and its derivatives amongst isolates of HLGR E. faecium, although a Gmr plasmid from an HLGR E. faecium isolated in the United States showed little homology with the other Gmr plasmids studied.
Insights
Widespread dissemination of a gentamicin resistance (Gmr) plasmid, not a specific clone, is suggested among high-level gentamicin-resistant (HLGR) Enterococcus faecium isolates globally. This indicates a common source for the resistance gene
Area of Science:
- Clinical microbiology
- Molecular epidemiology
- Antimicrobial resistance
Background:
- High-level gentamicin resistance (HLGR) in Enterococcus faecium poses a significant clinical challenge.
- Understanding the mechanisms and spread of gentamicin resistance (Gmr) is crucial for infection control.
Purpose of the Study:
- To investigate the molecular epidemiology of HLGR Enterococcus faecium isolates from multiple continents.
- To determine if clonal spread of a specific HLGR E. faecium strain or dissemination of a Gmr plasmid is responsible for resistance.
Main Methods:
- Analysis of eight clinical E. faecium isolates exhibiting high-level gentamicin resistance.
- Utilized ribotyping, plasmid profiling, and extended antimicrobial susceptibility testing.
- Restriction endonuclease digestion and cross-hybridization studies of Gmr plasmids.
Main Results:
- Isolates were generally distinct, refuting clonal dissemination of a single E. faecium strain.
- All isolates harbored closely related Gmr plasmids, suggesting widespread plasmid dissemination.
- The gentamicin resistance gene identified differed from previously characterized transposons.
Conclusions:
- The study strongly suggests the widespread dissemination of a single Gmr plasmid and its variants among HLGR E. faecium.
- This contrasts with clonal spread, highlighting the role of plasmids in the global spread of antibiotic resistance.
Related Concept Videos
01:25Mechanism of Antibiotic Resistance in MRSA
01:25Clinical Significance of Antibiotic Resistance