1. Streptococcus pyogenes
B. Knauss F2013
Modified by DYH
Streptococcus pyogenes
Gram positive cocci
Pathogenic human skin flora
Group A streptococci
Capable of beta-hemolysis; Complete clearing of red blood cells
Figure 2, S. pyogenes plated on blood agar
Phylum Firmicutes
Order Lactobacillales
Family Streptococcaceae
Utilize pili to attach to host
Figure 1;
Figure 2;

2. Streptococcus pyogenes Pathogenesis
B. Knauss F2013
Modified by DYH
Streptococcus pyogenes Pathogenesis
Respiratory and skin infections, namely tonsillitis and pneumonia
Spread by direct physical contact
Capsule forming
Capsule is non antigenic so it chemically matches the host’s connective tissue and is not targeted for phagocytosis
Figure 3, S. pyogenes cells appear black with a white “halo” around them
Contain M proteins, fimbrial proteins, fibronectin-binding proteins, and streptokinases on cell surface for adhesion to host
M proteins also aide in resistance to phagocytosis
Contain streptolysins, streptokinases, and hyaluronidase to break down host tissue and cause inflammation
Several million cases of strep throat and impetigo are reported each year in the United States
Severely susceptible to penicillin
Figure 3;