What is a free coagulase and its significance?

Answer 1

Free coagulase is an extracellular toxin that reacts with a thrombin-like, thermostable substance known as coagulase-reacting factor (CRF) or serum factor. The reaction of coagulase and CRF will lead to the formation of coagulase-CRF complex where this complex indirectly changes frbrinogen to fibrin (clotting factor) and hence will form a fibrin clot. Furthermore, it is also use as the primary indicator of virulence among staphylococci. Its clinical significance is that when doing the coagulase tube test, the free coagulase will react with the plasma in the tube and hence convert the fribrinogen into fibrin which lead to fibrin clot formation in the tube. This is shown after one day of incubation of the tube, when the tube being invert, the plasma will not go down showing that it is clotted.