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Modulation of virulence within a pathogenicity island in vancomycin-resistant Enterococcus faecalis
Nathan Shankar1, Arto S Baghdayan, Michael S Gilmore
1nathan-shankar@ouhsc.eduDepartment of Pharmaceutical Sciences, University of Oklahoma Health Sciences Center, PO Box 26901, Oklahoma City, Oklahoma 73190, USA.
Nature
|June 18, 2002
Summary
Researchers discovered a large pathogenicity island in Enterococcus faecalis, a common gut bacterium. This genetic element, varying subtly between strains, helps modulate virulence and identifies new disease targets not essential for normal gut function.
Area of Science:
- Microbiology
- Genomics
- Infectious Diseases
Background:
- Enterococci are part of normal human gut flora.
- They are also a major cause of hospital-acquired infections, often antibiotic-resistant.
- Previous research had not identified pathogenicity islands in this genus.
Purpose of the Study:
- To investigate the genetic basis of virulence in Enterococcus faecalis.
- To identify novel virulence factors and potential therapeutic targets.
Main Methods:
- Genome sequencing of two distinct Enterococcus faecalis strains (hospital outbreak strain and first US vancomycin-resistant isolate).
- Comparative genomic analysis to identify unique genetic elements.
- Analysis of the structure and variation within the identified pathogenicity island.
Main Results:
- A large (approx. 150 kb) pathogenicity island was identified in both strains, previously unknown in Enterococci.
- This island has a lower G+C content and is flanked by terminal repeats.
- Subtle, high-frequency variations within the island modulate bacterial virulence.
- The island contains known virulence factors and novel genes rare in non-pathogenic isolates.
Conclusions:
- The enterococcal pathogenicity island is a key factor in virulence.
- Variations in this island allow strains to adapt and cause infection.
- Novel genes on the island represent potential targets for new antimicrobial therapies.
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