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Multilocus sequence typing scheme for Enterococcus faecium.
Wieger L Homan1, David Tribe, Simone Poznanski
1Research Laboratory for Infectious Diseases, National Institute of Public Health and the Environment, Bilthoven, The Netherlands. wieger.homan@rivm.nl
Journal of Clinical Microbiology
|May 31, 2002
Summary
A new multilocus sequence typing (MLST) scheme for Enterococcus faecium reveals distinct genetic lineages in vancomycin-sensitive (VSEF) and vancomycin-resistant (VREF) strains. MLST is an excellent tool for characterizing E. faecium isolates and analyzing long-term epidemiology.
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Background:
- Enterococcus faecium is a significant opportunistic pathogen.
- Understanding the genetic diversity and population structure of E. faecium is crucial for infection control.
- Existing typing methods may not fully capture the global genetic variation within E. faecium.
Purpose of the Study:
- To develop and validate a multilocus sequence typing (MLST) scheme for Enterococcus faecium.
- To analyze the genetic diversity and population structure of E. faecium isolates from various sources and geographic locations.
- To investigate the genetic basis of epidemic lineages and host-specific clustering in E. faecium.
Main Methods:
- Development of an MLST scheme targeting seven housekeeping genes in E. faecium.
- Analysis of 139 E. faecium isolates from humans and livestock across multiple countries.
- Comparison of MLST data with amplified fragment length polymorphism (AFLP) analysis for host-specific clustering.
Main Results:
- A total of 62 distinct sequence types were identified among vancomycin-sensitive E. faecium (VSEF) and vancomycin-resistant E. faecium (VREF) isolates.
- VSEF isolates exhibited greater genetic diversity compared to VREF isolates.
- Both VSEF and VREF isolates showed host-specific lineage clustering, with outbreak isolates forming a distinct subgroup characterized by specific gene alleles.
Conclusions:
- The developed MLST scheme is a robust tool for E. faecium isolate characterization and long-term epidemiologic analysis.
- Epidemic E. faecium lineages appear to have emerged recently on a global scale.
- Long-term recombination events have contributed significantly to the genetic variation observed in both VREF and VSEF populations.