S. pyogenes

• Streptococcal pyrogenic exotoxins (Spe)

  • SpeA-D
  • Superantigens
• Diseases


  • Suppurative disease (pus producing)
  • Non-supparative (non pus forming, usually a complication due to infection causes supportive disease)
• Pharyngitis


  • Inflammation of the oropharynx
  • Can be viral and bacterial
  • Bacterial is caused by group A streptococcus, usually S. Pyrogenes (Strep throat)
• Symptoms of strep throat

  • Sore throat
  • Fever
  • Malaise
  • Headache
  • Characteristic erythematous rash on the back of throat (red rash caused by dilated and congested capillaries)
• Diagnosis of strep throat

  1. Throat swab for strep A antigen (lancefield A)

  2. Growth on BAP (beta hemolytic - confirm with gram stain)
• Scarlet Fever


  • Complication of streptococcal pharyngitis (strep throat)
  • Occurs when infecting A. Pyogenes contains a gene for Spe toxin
  • Inflammation causes erythematous rash on the upper chest and extremities 1-2 days after pharyngitis
  • Also strawberry rash on tongue (both clear in 5-7 days)
• Rheumatic Fever


  • Non-supparative disease
  • Another complication from strep throat
  • Chronic inflammation of the heart, joints, skin and brain
  • Caused by cross reactivity of anti streptococcal antibodies to host proteins
  • Antibody of M protein: cross react with myosin of the heart fibers
  • Immune system attack of heart valves - reduced heart function