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Strep pyogenes: Presentation

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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