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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
PubMed

Insights

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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