Streptococcal mitogenic exotoxins

Definition

Streptococcal mitogenic exotoxins are virulence factors produced by certain strains of Streptococcus bacteria that stimulate immune cells to proliferate uncontrollably. These exotoxins contribute to the pathogenicity and severity of infections caused by these bacteria.

5 Must Know Facts For Your Next Test

1. Streptococcal mitogenic exotoxins activate T-cells non-specifically, leading to a massive release of cytokines.
2. These exotoxins are classified as superantigens due to their ability to bypass normal antigen processing.
3. They are implicated in severe diseases such as streptococcal toxic shock syndrome (STSS) and necrotizing fasciitis.
4. Mitogenic exotoxins can cause an exaggerated immune response, resulting in systemic inflammation and tissue damage.
5. The genes encoding these exotoxins are often located on mobile genetic elements like prophages, facilitating their spread among different bacterial strains.

Review Questions

• What role do streptococcal mitogenic exotoxins play in the immune response?
• How do streptococcal mitogenic exotoxins contribute to the severity of infections?
• Why are streptococcal mitogenic exotoxins considered superantigens?

Related terms

Superantigen: A class of antigens that result in excessive activation of the immune system.

Cytokine Storm: An overproduction of immune cells and their activating compounds, which can lead to severe inflammation and tissue damage.

Prophage: A bacteriophage genome integrated into the DNA of a bacterial cell, often carrying genes that confer new properties such as toxin production.