Question

How does the enzyme coagulase function and what degree of clotting is regard as a positive reaction in the Enumeration and Identification of S.aureus test?

Answer 1

Ans - Function of coagulase- Coagulase reacts with prothrombin in the blood . The resulting complex is called staphylothrombin , which enables the enzyme protease to fibrinogen, which is a plasma protein produced by liver , into fibrin. This results in clotting of blood .Coagulase is tightly bound to the surface of bacterium Staphylococcus aureus and can coat it's surface with fibrin upon contact with blood.

Coagulase test is used to differentiate between Staphylococcus aureus (positive) from Coagulase negative staphylococcus . Coagulase produced by Staphylococcus aureus coverts soluble fibrinogen into insoluble fibrin with +4 positive reaction.