USMLE

Strep agalactiae

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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

Streptococcus agalactiae

  • Also known as Group B streptococcus
  • Characteristics
    • Gram + cocci
    • Catalase negative
      • First-test; determines staph (catalase positive) vs. strep 
    • Beta-hemolytic
      • Second test; determines subtype of strep or enterococci
    • PYR – 
      • Third test; used to rule out strep pyogenes (PYR+)
    • Bacitracin-resistant
      • Third test; also used to rule out strep pyogenes (PYR+), although bacitracin is not specific so it is less commonly used than PYR.
    • Produces CAMP factor = enlarges hemolysis by S aureus
      • CAMP stands for Christie-Atkins-Munch-Peterson
        • Note: this is NOT cAMP!! 
      • CAMP factor synergistically enhances action of beta-lysin produced by S. aureus, to increase area of hemolysis
    • Hippurate test +
    • Facultative anaerobe 
  • Presentation
    • Part of normal gastrointestinal and urogenital flora
    • pneumonia, meningitis, and sepsis
      • mainly in neonates
      • Transmitted during vaginal delivery from mother to neonates
    • Screen and Treat pregnant moms at 35-37 weeks of gestation
      • Using rectal and vaginal swabs
      • If positive → prophylaxis with penicillin
  • Treatment
    • Penicillin G
      • Penicillin G is the antibiotic of choice for this organism in both the colonized mother and the infected infant