What does the coagulase test determine?
The coagulase test identifies whether an organism produces the exoenzyme coagulase, which causes the fibrin of blood plasma to clot.
What 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.
What does catalase and coagulase positive mean?
Coagulase is an enzyme that clots blood plasma. This test is performed on Gram-positive, catalase positive species to identify the coagulase positive Staphylococcus aureus. Coagulase is a virulence factor of S. aureus.
What antibiotics treat coagulase positive staph?
The antibiotics tested for coagulase-positive and -negative staphylococcus were oxacillin, cefoxitin, vancomycin, moxifloxacin, ciprofloxacin, clindamycin, erythromycin, tobramycin, and cefazolin.
What bacteria can produce coagulase?
Coagulase is an enzyme that is produced by some types of bacteria . The enzyme clots the plasma component of the blood. The only significant disease-causing bacteria of humans that produces coagulase is Staphylococcus aureus.
What is the clinical significance of coagulase production?
What is the clinical significance of coagulase production? The bacteria is able to produce a clot that forms a protective barrier around the bacteria, preventing it from being attacked by phagocytic cells of our body.
What does coagulase do for a bacteria that has it?
Clinical isolates of Staphylococcus aureus secrete coagulases, polypeptides that bind to and activate prothrombin, thereby converting fibrinogen to fibrin and promoting the clotting of plasma or blood.
What Staphylococcus are catalase positive?
Staphylococcus and Micrococcus spp. are catalase positive, whereas Streptococcus and Enterococcus spp. are catalase negative.
Is Streptococcus coagulase positive?
Gram-positive cocci include Staphylococcus (catalase-positive), which grows clusters, and Streptococcus (catalase-negative), which grows in chains. The staphylococci further subdivide into coagulase-positive (S. aureus) and coagulase-negative (S. epidermidis and S.
What is coagulase positive staphylococci?
Abstract. Staphylococcus aureus and other coagulase-positive staphylococci (CoPS) are opportunistic pathogens associated with a large spectrum of diseases that range from skin and mucosal infections to life-threatening septicemias in humans and animals.
Is Staphylococcus Saprophyticus coagulase positive?
Staphylococcus saprophyticus is a Gram-positive, coagulase-negative, non-hemolytic coccus that is a common cause of uncomplicated urinary tract infections (UTIs), particularly in young sexually active females.
Is Staphylococcus epidermidis coagulase positive?
Staphylococcus epidermidis is a coagulase-negative, gram-positive cocci bacteria that form clusters. It is also a catalase-positive and facultative anaerobe. They are the most common coagulase-negative Staphylococcus species that live on the human skin.
What is the purpose of a coagulase test?
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).
What is the principle of coagulase?
Principle of Coagulase Test. Coagulase is an enzyme-like protein and causes plasma to clot by converting fibrinogen to fibrin. Staphylococcus aureus produces two forms of coagulase: bound and free. Bound coagulase (clumping factor) is bound to the bacterial cell wall and reacts directly with fibrinogen.
What does it mean when a slide clumps?
Clumping in both drops of slides indicates that the organism auto agglutinates and is unsuitable for the slide coagulase test. All the negative slide test must be confirmed using the tube test.
Why is no plasma added to the second suspension?
No plasma is added to the second suspension to differentiate any granular appearance of the organism from true coagulase clumping.
How much plasma is pipetted into each tube?
Pipette 0.5 ml of the diluted plasma into each tube.
Does free coagulase require coagulase-reacting factor?
This doesn’t require coagulase-reacting factor. Free coagulase involves the activation of plasma coagulase-reacting factor (CRP), which is a modified or derived thrombin molecule, to from a coagulase-CRP complex. This complex in turn reacts with fibrinogen to produce the fibrin clot.
What is the purpose of coagulase test?
Coagulase test is used to differentiate Staphylococcus aureus (positive) from Coagulase Negative Staphylococcus (CONS). 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 long does it take for a cocci to show up on a tube coagulase test?
Read as positive a coarse clumping of cocci visible to the naked eye within 10 seconds. Read as negative the absence of clumping or any reaction taking more than 10 seconds to develop, but re-examine any slow reacting strains by the tube coagulase test.
What is the main method used to identify S. aureus in clinical laboratories?
Interpretation: Slide coagulase test is the main method used to identify S. aureus in clinical laboratories but it has some limitations.
How long does it take for a clot to form?
Clot formation within 4 hours indicates a positive test. Positive test indicates Staphylococcus aureus. Some species of Coagulase negative staphylococcus can be positive. Negative tubes should be held overnight at room temp. Some species possess enzyme that can cause the dissolution of clot after prolonged incubation.
Why make similar suspensions of control positive and negative strains?
Make similar suspensions of control positive and negative strains to confirm the proper reactivity of the plasma.
Is coagulase negative for staph?
Coagulase Negative: No clot (plasma remains wholly liquid or shows only a flocculent or ropy precipitate). eg. Staphylococcus epidermidis
What is the purpose of a coagulase test?
A coagulase test is a biochemical test that is used to differentiate Staphylococcus aureus from other Staphylococci species like S. epidermidis and S. saprophyticus on the basis of the ability to produce the coagulase enzyme . The coagulase test is an important test that differentiates the species of the genus Staphylococci into two groups;
What is the role of coagulase enzyme in virulence?
The coagulase enzyme acts as a virulence factor in some organisms as it interacts with the fibrinogen present on the host’s cell surface.
What is the difference between free coagulase and bound coagulase?
Free coagulase is different from bound coagulase in that the clotting mechanism of free coagulase requires the activation of a plasma coagulase-reacting factor (CRF), which is a modified or derived thrombin molecule, to form a coagulase-CRF complex .
How is the presence of the clumping factor demonstrated?
The presence of the clumping factor is demonstrated by the ability of the organism to act directly on the fibrinogen in the plasma to clump it in a slide assay.
What is the protective barrier of coagulase?
Organisms with coagulase usually have a protective barrier around themselves, increasing their pathogenicity and resistance against the immune system. Coagulase is of two types; free coagulase and bound coagulase, each of which is detected by different methods.
How to detect coagulase?
Coagulase can be detected by two different methods; tube test and slide test.
How long does it take for rabbit plasma to clump?
A drop of a rabbit or human plasma is added to the slide, and the clumping is observed immediately, not to exceed 10 seconds.
How many species of staphylococci are there?
21.2 Staphylococci in the Food Industry. The genus Staphylococcus comprises more than 50 validly described species that are grouped traditionally into coagulase-positive staphylococci (CoPS) and coagulase-negative staphylococci (CoNS).
What is the requirement for screening of SEs?
European regulations (EC 2073/2005 and 1441/2007) require screening of SEs if CPS counts in milk products during the manufacturing process at the processing step exceed 10 5 CFU g − 1. Commercial toxin detection kits (such as Vidas® SET2 kit or Ridascreen® SET Total kit) have been recommended for this purpose by the National and European Union Reference Laboratories for Coagulase Positive Staphylococci. The different types of methods available for detection and investigation of bacterial toxins in food are based on bioassays, immunologic techniques, molecular biology, and mass spectrometry-based methods.
Which staphylococci are coagulase negative?
The coagulase-negative staphylococci include S. epidermidis and S. saprophyticus. Coagulase-negative staphylococci, of which S. epidermidis is the most prominent, are nosocomial pathogens responsible for wound infections and infections of indwelling foreign bodies and intravenous catheters.
What causes skin lesions in Great Apes?
Bacterial culture of the skin lesions followed by antibiotic sensitivity testing revealed that the lesions were caused by a meticillin-resistant staphylococcal infection and the animal was euthanized. There are two reports of staphylococcal infection in great apes.
What is a CoPS?
Staphylococcus aureus and other coagulase-positive staphylococci (CoPS) are opportunistic pathogens associated with a large spectrum of diseases that range from skin and mucosal infections to life-threatening septicemias in humans and animals.
Why is food analysis complex?
In the case of food analysis, the situation is complex because the matrix can contain many proteins, lipids, and many other molecular species that interfere with the detection of the targeted toxin and may distort quantification . Sample preparation remains the critical step of the analysis. It could be improved by, for example, optimizing digestion parameters or by adding a purification step. The strategy of incorporating an isotopically labeled internal standard into the samples has also been developed.
How to incubate a plate?
Inoculate poured plates and incubate overnight at 37°C. Expose each plate to ammonia vapour by adding a few drops of ammonia to a filter paper inserted in the lid of the dish.
What is the principle of coagulase?
Principle Coagulase is an enzyme produced by S. aureus that converts (soluble) fibrinogen in plasma to (insoluble) fibrin. Calcium is required for the conversion of prothrombin to thrombin which eventually converts fibrinogen to fibrin leading to the formation of a clot. Citrate added in the plasma reacts with calcium to form calcium citrate. Thus calcium is unavailable and there is no clot formation. If the organism produces coagulase enzyme, coagulase will react with coagulase reacting factor and form a complex. This complex converts prothrombin to thrombin which eventually converts fibrinogen to fibrin leading to the formation of a clot (positive)
What is the enzyme that produces coagulate?
Coagulase is an enzyme produced by Staph.aureus. In test, the plasma fibrinogen is converted in to fibrin (coagulate) where it is differentiated from other cocci.
What is the coagulase test used for?
The coagulase test has traditionally been used to differentiate Staphylococcus aureus from coagulase-negative staphylococci. S.aureus produces two forms of coagulase (i.e., bound coagulase and free coagulase). Bound coagulase, otherwise known as "clumping factor", can be detected by carrying out a slide coagulase test, and free coagulase can be detected using a tube coagulase test.
How many citrated plasmas are needed for autocoagulation?
Requirement- 1 in 10 citrated plasma (citrated to present auto-coagulation in absence of coagulase enzyme)
What is a slide coagulase test?
A slide coagulase test is run with a negative control to rule out autoagglutination. Two drops of saline are put onto the slide labeled with sample number, Test (T) and control (C). The two saline drops are emulsified with the test organism using a wire loop, straight wire, or wooden stick. A drop of plasma (rabbit plasma anticoagulated with EDTA is recommended)
Why doesn't blood coagulate in bood test tubes?
Blood doesn't coagulate when extracted in bood test tubes or vacutainers because they contains anticoagulants.
What happens if a colony is positive?
If 'positive' (e.g., the suspect colony is S. aureus ), the plasma will coagulate, [6] resulting in a clot (sometimes the clot is so pronounced, the liquid will completely solidify).
Introduction to Coagulase Test
Principle of Coagulase Test
- Coagulase is an enzyme-like protein and causes plasma to clot by converting fibrinogen to fibrin.Staphylococcus aureusproduces two forms of coagulase: bound and free. 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, caus…
Procedure and Types of Coagulase Test
- Slide Test
1. Place a drop of physiological saline on each end of a slide, or on two separate slides. 2. With the loop, straight wire or wodden stick, emulsify a portion of the isolated colony in each drops to make two thick suspensions. 3. Add a drop of human or rabbit plasma to one of the suspension… - Tube Test
1. Dilute the plasma 1 in 10 in physiological saline ( mix 0.2 ml of plasma with 1.8 ml of saline). 2. Take 3 small test tubes and label as T (Test), P (Positive Control) and N (Negative Control). Test is 18-24 hour broth culture, Positive control is 18-24 hr S. aureus broth culture and Negative cont…
Interpretation of Coagulase Test
- (Picture Source: University of Malta, Msida MSD 2080, Malta) Fibrin Clot of any size- Positive No Clot- Negative 1. Clumping in both drops of slides indicates that the organism auto agglutinates and is unsuitable for the slide coagulase test. All the negative slide test must be confirmed using the tube test. 2. During slide test, there may be chance to false positive results in case of citrate …
Examples
- Coagulase Positive Organisms: Staphylococcus aureus and other animal host bacteria likeS. pseudintermedius, S. intermedius, S. schleiferi, S. delphini, S. hyicus, S. lutrae, S. hyicus Coagulase Negative Organisms: Staphylococcus epidermidis, S. saprophyticus, S. warneri, S. hominis, S. caprae, etc.
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