USMLE

Enterococcus

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Bacteria - Gram Positive
  1. Staph aureus: Overview
  2. Staph aureus: Presentation
  3. Methicillin-Resistant Staph aureus (MRSA)
  4. Staph saprophyticus
  5. Strep pneumoniae: Overview
  6. Strep pneumoniae: Presentation
  7. Strep viridans
  8. Strep pyogenes: Overview
  9. Strep pyogenes: Presentation
  10. Strep agalactiae
  11. Strep bovis
  12. Enterococcus
  13. Bacillus anthracis
  14. Bacillus cereus
  15. Clostridium tetani
  16. Clostridium perfringens
  17. Clostridium botulinum
  18. Clostridium difficile
  19. Corynebacterium diphtheriae
  20. Listeria monocytogenes
  21. Nocardia
  22. Actinomyces

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