Streptococcus Pyogenes (Group A Strep)

Question 1

Morphology

Answer 1

Gram Positive Cocci in pairs and chains

Encapsulated, facultative anaerobe

Question 2

Classification/Diagnosis

Answer 2

Catalase Negative
Beta-hemolytic
Bacitracin sensitive

Test by microscopy, rapid strep test, culture, anti-DNAse B or anti-streptolysin O tests

Question 3

Pathology

Answer 3

Exotoxins - (SpeA, B, C, F)
Hyaluronic acid capsule, hyaluronidase
C5a peptidase (inhibits complement mediated chemoattraction)
M Protein (prevents phagocytosis

Question 4

Epidemiology

Answer 4

Colonizes oropharynx of children and young adults, pharyngitis in children 5-15 years of age

spread person to person and through breaks in skin, higher risk in winter months

Question 5

Diseases/Symptoms

Answer 5

Pharyngitis
cutaneous infections (scarlet fever, impetigo, necrotizing fasciitis)
invasive infections (bacteremia, septic arthritis, pneumonia)
toxic shock-like syndrome
non-suppurative sequelae (rheumatic fever, acute glomerulonephritis)

Question 6

Treatment/Vaccination

Answer 6

Penicillin
treatment of pharyngitis prevents rheumatic fever
Antibiotic prophylaxis needed for history of rheumatic fever