What is the Difference Between Streptolysin O and Streptolysin S?

Streptolysin O (SLO) and Streptolysin S (SLS) are both hemolysins produced by Streptococcus bacteria, but they have distinct differences:

1. Oxidative stability: Streptolysin O is oxygen-labile, meaning it is active only under reversibly reduced states, while Streptolysin S is oxygen-stable and remains active in the presence of atmospheric oxygen.
2. Antigenicity: Streptolysin O is antigenic, meaning it can stimulate an immune response, while Streptolysin S is not due to its relatively small size.
3. Production: Streptolysin O is produced during exponential and early stationary-phase growth, while Streptolysin S is primarily produced during stationary-phase growth in broth culture.
4. Hemolytic activity: Both Streptolysin O and Streptolysin S are involved in the formation of zones of β hemolysis around streptococci colonies grown on blood agar.
5. Toxicity: Both compounds are toxic to leucocytes, platelets, and many cell lines. They can cause various effects on target cells in vitro and, in laboratory animals, intravenous administration of small quantities of purified SLO can cause death with cardiotoxicity being the prominent pathophysiological effect.

In summary, Streptolysin O and Streptolysin S are both hemolysins produced by Streptococcus bacteria, but they differ in their oxidative stability, antigenicity, production phases, and structure.

Comparative Table: Streptolysin O vs Streptolysin S

Here is a table comparing the differences between Streptolysin O (SLO) and Streptolysin S (SLS):

Streptolysin O is an oxygen-labile hemolytic exotoxin produced by Streptococcus bacteria, while Streptolysin S is an oxygen-stable hemolytic exotoxin produced by the same bacteria. Both toxins contribute to the virulence of Streptococcus pyogenes infections, but they have different molecular properties and effects on target cells.