BoardVitals Microbiology Practice Test

The major virulence factor of Streptococcus pyogenes is linked to its ability to secrete exotoxins. These exotoxins, such as streptolysins and pyrogenic exotoxins, play a crucial role in the pathogenicity of the bacterium. They contribute to tissue damage, immune evasion, and the overall inflammatory response. For instance, streptolysin S and O help lyse red and white blood cells, facilitating the spread of the infection and undermining the host’s immune defense.

This characteristic allows S. pyogenes to cause a variety of diseases, such as pharyngitis (strep throat), skin infections, and more severe conditions like necrotizing fasciitis and toxic shock syndrome. The ability to produce these exotoxins is a key reason why some S. pyogenes strains are more virulent than others.

In contrast, while capsule formation does occur among some strains, it is not the primary virulence factor attributed to S. pyogenes. Endotoxin production is associated primarily with Gram-negative bacteria, and biofilm formation is not a significant factor for this particular pathogen, as it does not adhere to surfaces in the same way that other bacteria might to form bio