USMLE

Strep pyogenes: Presentation

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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

Strep pyogenes presentation/complications: 

  • Presentation:
    • Pharyngitis
    • Skin infections
      • Impetigo
        • “honey/golden-crusted” lesions
      • Erysipelas
        • painful red plaque with raised borders
      • Cellulitis
    • Can cause hematogenous osteomyelitis, necrotizing fasciitis
    • Scarlet fever
      • Caused by pyrogenic exotoxin
      • Blanching, sandpaper-like rash, strawberry tongue, and circumoral pallor in the setting of group A streptococcal pharyngitis
        • Erythrogenic toxin +
    • Toxic shock-like syndrome
      • Caused by pyrogenic exotoxin
      • Caused by a superstimulation of T cells 
      • Necrotizing fasciitis
  • Complications
    • Rheumatic fever
      • Usually follows untreated pharyngitis, not skin infections
      • antibodies against M protein or other virulence factors (e.g. streptolysin O) can attack self-tissues
        • Similarity of M protein to self-cells is due to molecular mimicry
          • may help the bacteria avoid detection by immune system
      • Presentation:
        • Migratory polyarthritis 
        • Endocarditis
          • presents as acute development of mitral regurgitation
          • Many years later, chronic lesion can present as mitral stenosis 
    • Poststreptococcal Glomerulonephritis
      • Usually occurs 1-2 weeks after GAS infection (e.g. skin, pharynx)
      • Facial edema, dark cola-colored urine, hematuria
      • Caused by immune complex deposition (Type III Hypersensitivity Reaction) 
      • Strains causing impetigo can induce glomerulonephritis