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Enterococcus

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Enterococci 

  • E faecalis and E faecium
  • Gram + cocci in pairs (diplococci) or short chains
    • Difficult to distinguish vs. streptococci by physical characteristics alone
  • Catalase – 
  • PYR +
  • Gamma (not) Hemolytic
    • Rarely can be alpha-hemolytic
  • Highly resilient
    • can grow in hypertonic (6.5%) NaCl and bile
  • Presentation generally follows GI/GU procedures
    • Part of normal intestinal and urogenital flora, introduced to bloodstream following procedures (foley catheter, cystoscopy, colonoscopy)
    • UTI
      • Most common infection caused by enterococcus
    • Biliary tract infection
      • Related to its ability to grow in bile
    • Subacute endocarditis 
  • VRE (vancomycin-resistant enterococci)
    • important cause of nosocomial infection
    • Alters the vancomycin-binding site from a D-alanyl-D-alanine terminus to a D-alanine-D-lactate terminus
    • Resistance gained through uptake of resistance plasmid 
  • Treatment is dependent on susceptibility testing: 
    • Amoxicillin, fosfomycin, or nitrofurantoin for UTI 
    • Ampicillin, vancomycin, daptomycin for sepsis
    • Ampicillin and gentamicin for endocarditis
    • Linezolid for VRE