What is the principle of the coagulase test?
Principle of Coagulase Test
Bound coagulase (clumping factor) is bound to the bacterial cell wall and reacts directly with fibrinogen. This results in an alternation of fibrinogen so that it precipitates on the staphylococcal cell, causing the cells to clump when a bacterial suspension is mixed with plasma.
What is the mechanism of action for coagulase?
Coagulase reacts with prothrombin in the blood. The resulting complex is called staphylothrombin, which enables the enzyme to act as a protease to convert fibrinogen, a plasma protein produced by the liver, to fibrin. This results in clotting of the blood.
What is a coagulase positive test?
The tube coagulase test is a valid means of identifying Staphylococcus aureus, provided that only a firm clot that does not move when the tube is tipped is considered a positive reaction. The widely promulgated interpretation that all degrees of clotting in coagulase plasma are a positive identification of S.
What reagent is used in coagulase test?
rabbit plasma
The Tube Coagulase Test consists of putting approximately 1 ml of coagulase reagent (rabbit plasma) in a labeled test tube and incubating it at 34 to 37 degrees Celsius from 4 to 24 hours. If the tube has a thick, solid clot within 24 hours, it is Staphylococcus aureus.
What are the 2 types of coagulase test?
Coagulase is of two types; free coagulase and bound coagulase, each of which is detected by different methods. The bound coagulase is called the clumping factor and is detected rapidly by a slide test. The free coagulase, in turn, is detected in the test tube as a result of the formation of a clot.
Why is plasma used in coagulase test?
The slide test is performed by preparing a suspension of bacterial cells mixed into a drop of EDTA-treated rabbit plasma on a microscope slide. If bound coagulase is present on the bacterial cells, then the presence of plasma will cause the bacterial cells to clump.
Which bacteria is coagulase-positive?
Bacteria in the genus Staphylococcus are pathogens of man and other mammals. Traditionally they were divided into two groups on the basis of their ability to clot blood plasma (the coagulase reaction). The coagulase-positive staphylococci constitute the most pathogenic species S aureus.
Which bacteria is coagulase positive?
Why is coagulase important?
The role of coagulase can cause the formation of a fibrin layer around the staphylococcal abscess, the infection is localized, and the microorganisms are protected from phagocytosis (Tam and Torres, 2019).