What is the purpose of a coagulase test?
What is the purpose of a coagulase test?
The coagulase test identifies whether an organism produces the exoenzyme coagulase, which causes the fibrin of blood plasma to clot.
What is the purpose of using coagulase enzyme?
Coagulase is a protein enzyme produced by several microorganisms that enables the conversion of fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of Staphylococcus isolates.
How does the coagulase test help confirm the presence of S aureus?
Coagulase testing is the single most reliable method for identifying Staphylococcus aureus [9]. Slide coagulase detects bound coagulase (also called “clumping factor”) [9], which reacts directly with fibrinogen in plasma, causing rapid cell agglutination.
How would you interpret a negative slide test?
How would you interpret a negative slide test and a positive tube test using the same organism? The slide test detects bound coagulase; the tube test detects both bound and free. A negative slide test indicates absence of bound coagulase, but positive tube indicates presence of free.
What is the difference between the slide and tube test for coagulase?
Slide coagulase test is done to detect bound coagulase or clumping factor. Tube coagulase test is done to detect free coagulase.
Which bacteria is the coagulase test useful for identification?
Coagulase test is used to differentiate Staphylococcus aureus (positive) which produce the enzyme coagulase, from S. epidermis and S. saprophyticus (negative) which do not produce coagulase. i.e Coagulase Negative Staphylococcus (CONS).
Why should a negative coagulase slide test be confirmed by the tube test?
Clumping factor acts directly on the fibrinogen in the plasma resulting in clumping. Slide coagulase test is rapid, but it requires several colonies and lacks sensitivity. As the clumping factors are not present in all S. So, the negative slide tests must be confirmed by tube coagulase test.
How does coagulase help some Staphylococcus cell during infection?
Clinical isolates of the human pathogen Staphylococcus aureus secrete coagulase (Coa), a polypeptide that binds to and activates prothrombin, thereby converting fibrinogen to fibrin and promoting clotting of plasma or blood.
What is coagulase positive staph?
Coagulase positive staphylococci are known human pathogens. Transmission of these organisms occurs through direct contact with colonized or infected persons or through indirect contact with contaminated objects. S. aureus is the most common species in this group; additional species include S. lugdunensis and S.
Why is plasma used in coagulase test?
The formation of a clot in the plasma indicates coagulase production. The tube test is the most frequently used method because of its greater accuracy and its ability to detect both bound and free coagulase. Coagulase Plasma is lyophilised rabbit plasma to which EDTA has been added as the anticoagulant.
What do you need to know about the slide coagulase test?
Slide Coagulase Test Slide coagulase test is done to detect “bound coagulase” or “clumping factor”. Clumping factor is a fibrinogen binding cell surface receptor present in cell wall of most, but not all, S. aureus. Clumping factor acts directly on the fibrinogen in the plasma resulting in clumping.
Which is the clumping factor in a coagulase test?
The bound coagulase is known as the “clumping factor”, which can be easily detected by using slide coagulase test, while a free coagulase can be detected by using a tube coagulase test. To describe how pathogenic species of Staphylococci can be differentiated from nonpathogenic species. To understand the biochemistry of the enzyme coagulase.
How is the coagulase test used to differentiate organisms?
The coagulase test differentiates organisms into two categories (coagulase-positive and coagulase-negative bacteria). Coagulase positive microorganisms produce bound and free coagulase enzyme. The bound coagulase combines with the fibrinogen protein of blood plasma and ultimately leads to the precipitation or clumping of fibrinogen.
What causes the lumpy look in a coagulase slide?
Bound coagulase reacts with the fibrinogen in plasma, causing the fibrinogen to precipitate. This causes the cells to agglutinate, or clump together, which creates the “lumpy” look of a positive coagulase slide test. You may need to place the slide over a light box to observe the clumping of cells in the plasma.
