Enterococcus species

Background

Microbiology

• Facultative anaerobic, non-spore-forming, gamma-hemolytic, Gram positive diplococci
• Commensal gut flora
• Increasing antibiotic resistance

Species

• E. faecalis
  • More common (90-95%)
  • More commonly genitourinary source
  • More sensitive to antibiotics
• E. faecium
  • Less common (5-10%)
  • More commonly gastrointestinal source
  • Less sensitive to antibiotics
  • Most common VRE
• E. gallinarum
• E. casseliflavus

Resistance

• Vancomycin binds to d-Ala-d-Ala pentapeptids, interfering with cell wall synthesis
• VanA: most common. Mutation to d-Ala-d-Lac, leading to high resistance to glycopeptides.
• VanB: more common in E. faecium in Australia
• VanC: chromosomal resistance on E. gallinarum and E. casseliflavus