Betahemolysins

Betahemolysins are a group of toxins produced by certain bacteria, most notably by species of Staphylococcus. These toxins are a type of hemolysin, meaning they are capable of lysing, or breaking down, red blood cells. The "beta" designation refers to the pattern of hemolysis observed when the bacteria are grown on blood agar. Betahemolysins produce a clear zone around the bacterial colonies because they completely lyse all red blood cells in the agar. This is in contrast to alphahemolysins, which produce an incomplete, greenish zone, and gammahemolysins, which produce no zone of hemolysis.

The primary betahemolysin produced by Staphylococcus aureus is known as gamma-hemolysin. However, the term betahemolysin is often used more broadly to encompass various staphylococcal toxins that exhibit complete hemolysis. These toxins are pore-forming proteins that insert themselves into the membranes of red blood cells, disrupting their integrity and leading to cell death. Betahemolysins can also affect other cell types, including white blood cells, and play a role in the virulence of pathogenic bacteria by contributing to tissue damage and inflammation. Their presence is often detected in laboratory settings as part of bacterial identification and characterization.