Virulence factors and clinical features of streptococcus pyogenes: Overview *

S. pyogenes is a facultative anaerobe, and the optimal temperature for growth is 37 °C. A nutrient-rich medium is required for S. pyogenes growth, and both blood and serum can promote its growth. Colonies growing on MS agar are shown in Figure 5.3(C). Cells from overnight blood agar plate culture have three different colony types: (1) colonies with β-hemolytic zone; (2) mucoid colonies; (3) lackluster colonies. In fact, the type of colony is mainly related to the growth condition and production of hyaluronidases.S. pyogenes can produce severapathogenic virulencefactors,including bacteriocins, hemolysin O, streptokinase, NADH enzyme, hyaluronidase, and M protein. The main sites of colonization for S. pyogenes are the dental plaque, hypopharynx, and the upper respiratory tract. Clinical samples can be isolated from skin lesions, inflammatory secretions, or blood. S. pyogenes can also be found in loose connective tissue inflammation in the maxillofacial region, pulpitis, or infection after exelcymosis.