Which toxin of streptococcus causes hemolysis?
**Core Concept**
Streptococcal hemolysis is a result of the enzymatic action of specific toxins produced by certain strains of Streptococcus. This process involves the breakdown of red blood cells, leading to hemolysis. The toxin responsible for this process is a key virulence factor in certain streptococcal infections.
**Why the Correct Answer is Right**
The correct toxin responsible for hemolysis in Streptococcus is streptolysin O (SLO). This toxin is a thiol-activated cytolysin that forms pores in the cell membrane of red blood cells, leading to cell lysis and hemolysis. Streptolysin O is produced by Streptococcus pyogenes and is a major contributor to the pathogenesis of invasive streptococcal infections.
**Why Each Wrong Option is Incorrect**
* **Option A:** Streptolysin S is another toxin produced by Streptococcus pyogenes, but it is primarily responsible for inhibiting the activity of complement on the bacterial surface, rather than causing direct hemolysis.
* **Option B:** Pyrogenic exotoxins are a group of toxins produced by Streptococcus pyogenes that cause fever and rash, but are not directly involved in hemolysis.
* **Option C:** Streptodornase is an enzyme produced by Streptococcus pyogenes that breaks down DNA, but it is not responsible for hemolysis.
**Clinical Pearl / High-Yield Fact**
Streptolysin O is a key virulence factor in Streptococcus pyogenes infections and is responsible for the characteristic hemolysis seen in blood cultures. It is also a major contributor to the pathogenesis of invasive streptococcal infections such as necrotizing fasciitis and streptococcal toxic shock syndrome.
**Correct Answer:** C.