What is the procedure for coagulase test?

Procedure and Types of Coagulase Test Add a drop of human or rabbit plasma to one of the suspensions, and mix gently. Look for clumping of the organisms within 10 seconds. No plasma is added to the second suspension to differentiate any granular appearance of the organism from true coagulase clumping.

What reagent is used for coagulase test?

rabbit plasma
The Tube Coagulase Test detects free coagulase which is an enzyme excreted outside the cell wall by the bacteria. 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.

What is the purpose of the coagulase test?

Coagulase is a virulence factor of S. aureus. The formation of clot around an infection caused by this bacteria likely protects it from phagocytosis. This test differentiates Staphylococcus aureus from other coagulase negative Staphylococcus species.

What is the meaning of coagulase?

Definition of coagulase : any of several enzymes that cause coagulation (as of blood)

Which chemical is used for catalase test?

hydrogen peroxide solution
Tube Method. Pour 1-2 ml of hydrogen peroxide solution into a test tube. Using a sterile wooden stick or a glass rod, take several colonies of the 18 to 24 hours test organism and immerse in the hydrogen peroxide solution. Observe for immediate bubbling.

What bacteria are 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.

What is the principle of catalase test?

PRINCIPLE: The breakdown of hydrogen peroxide into oxygen and water is mediated by the enzyme catalase. When a small amount of an organism that produces catalase is introduced into hydrogen peroxide, rapid elaboration of bubbles of oxygen, the gaseous product of the enzyme’s activity, is produced.

What is the difference between coagulase positive and negative?

If ‘positive’ (e.g., the suspect colony is S. aureus), the plasma will coagulate, resulting in a clot (sometimes the clot is so pronounced, the liquid will completely solidify). If ‘negative’, the plasma remains a liquid.

What is the pH of liver?

about pH 7
Different tissues in the body have different pHs (pH is a measure of how basic or acidic a solution is). The liver maintains a neutral pH (about pH 7), which is easiest for its enzymes, such as catalase, to work in.

Why is hydrogen peroxide used in catalase test?

The catalase test tests for the presence of catalase, an enzyme that breaks down the harmful substance hydrogen peroxide into water and oxygen. If an organism can produce catalase, it will produce bubbles of oxygen when hydrogen peroxide is added to it.

What bacteria is coagulase positive?

Why is pH 7 GOOD enzymes?

Catalase pH Levels In humans, catalase works only between pH 7 and pH 11. If the pH level is lower than 7 or higher than 11, the enzyme becomes denaturated and loses its structure. The liver sustains a neutral pH of about 7, which creates the best environment for catalase and other enzymes.

What is the pH of the lungs?

The pH in healthy lungs is between 7.38 and 7.42, equivalent to the pH of the blood that travels through the body [5]. By altering the concentration of carbon dioxide exhaled the lungs can monitor and maintain pH in the body [1].

What are the four types of catalase?

Catalases have been classified into three groups: monofunctional heme-containing catalases, heme-containing catalase-peroxidases, and manganese-containing catalases [7].

What color is catalase?

A stable purple color results when a reagent solution is applied to a smear of catalase-positive organisms streaked on a glass slide.

How to perform a coagulase test?

Procedure of Coagulase Test Place a drop of coagulase plasma (preferably rabbit plasma with ethylenediaminetetraacetic acid [EDTA]) on a clean, dry,… Place a drop of distilled water or saline next to the drop of plasma as a control. With a loop, straight wire, or wooden stick, emulsify a portion

What is bound coagulase in a slide test?

The clumping factor, termed bound coagulase, can be detected rapidly in the slide test, but this test requires several colonies and lacks sensitivity. S. aureus produces another substance in its cell wall, protein A, which binds to the F C moiety of human immunoglobulin G (IgG) and thus acts as a coagulase-reacting factor.

What is the function of coagulase?

Coagulase is an enzyme produced by S. aureus that converts soluble fibrinogen in plasma to insoluble fibrin. Staphylococcus aureus produces two forms of coagulase, bound and free.

How do you prepare coagulase tubes for clot formation?

So the tube coagulase tubes must be examined periodically (1, 2, and 4 hours) for clot formation. Negative tubes should be held overnight at room temperature. Prepare a 1-in-6 dilution of the plasma in saline (0.85% NaCl) and place 1 ml volumes of the diluted plasma in small tubes.