Streptolysin

Streptolysin is a type of toxin produced by certain species of Streptococcus. There are two types of streptolysin: Streptolysin O (SLO) and Streptolysin S (SLS). Both are hemolysins, which means they have the ability to lyse red blood cells in a culture medium.

Streptolysin O

Streptolysin O is an oxygen-labile enzyme and its activity is inhibited by oxygen. It is also antigenic, meaning it can stimulate an immune response. The presence of antibodies against SLO, known as anti-streptolysin O (ASO), can be detected in a person's blood. This is often used in a clinical setting to confirm a past streptococcal infection.

Streptolysin S

Streptolysin S is an oxygen-stable enzyme and its activity is not inhibited by oxygen. Unlike SLO, SLS is not antigenic and does not stimulate an immune response. It is responsible for the beta-hemolysis observed in blood agar cultures of certain Streptococcus species.

Clinical significance

Streptolysin is a major virulence factor of Streptococcus species. It allows the bacteria to lyse red blood cells and escape the immune response. High levels of ASO in a person's blood can indicate a recent streptococcal infection, such as rheumatic fever or glomerulonephritis.

See also

• Streptococcus
• Hemolysin
• Toxin
• Rheumatic fever
• Glomerulonephritis