Streptococcus pyogenes (Groups A, B, C, G, F)

Streptococcus pyogenes (Groups A, B, C, G, F)

Background:

Streptococcus pyogenes:

• Spherical, Gram-positive bacterium.
• Cause of group A streptococcal infections (displays streptococcal group A antigen on its cell wall).
• S. pyogenes typically produces large zones of beta-hemolysis when cultured on blood agar plates.
• Streptococci are catalase-negative.
• Has an incubation period of approximately 1–3 days.
• It is estimated that there are more than 700 million infections world wide each year and over 650,000 cases of severe, invasive infections that have a mortality rate of 25%.
• S. pyogenes is the cause of many important human diseases, ranging from mild superficial skin infections to life-threatening systemic diseases.
• Infections typically begin in the throat or skin. Examples of mild S. pyogenes infections include pharyngitis (“strep throat”) and localized skin infection (“impetigo”).

Therapy:

1. Amoxicillin 500mg orally three times daily or Ampicillin 2 grams IVPB every 4-6 hours
2. Penicillin G 2-4 million units IV q4-6h or Penicillin VK 500mg orally every 6 hours
3. Clindamycin  600mg IV every 6 or 8 hours or 300mg orally four times daily 
4. Ampicillin-sulbactam 1.5 – 3 grams IV q6h
5. Ceftriaxone 1-2 grams IV q24h
6. Others