Can we use citrated rabbit plasma for coagulase testing?
Some species or organisms utilize citrate in their metabolism and may yield false-positive reactions for coagulase activity. Normally this would not cause problems since the coagulase test is performed on staphylo- cocci almost exclusively. The presence of EDTA in the coagulase plasma should overcome this problem.
Why rabbit plasma is preferable in coagulase test?
Note: Rabbit plasma is preferable, as it gives better clotting, is free from inhibitors, and is safe. Human plasma contains sodium citrate as an anticoagulant, and some citrate utilizing bacteria such as Enterococcus faecalis can destroy the anticoagulant and cause clotting.
Why human plasma is not used in coagulase test?
Slide Test (to detect bound coagulase) 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.
Is human plasma used in coagulase test?
Coagulase testing is the most widely used in vitro test to determine the potential pathogenicity of staphylococci. We demonstrated that human plasma gives results comparable to those obtained with commercial rabbit plasma; however, positive and negative controls must be included in all coagulase procedures.
What is the purpose of EDTA in coagulase broth?
Coagulase Plasma EDTA is used for the identification of pathogenic Staphylococci, principally S. aureus by means of the coagulase test. When the strain is placed in contact with rabbit plasma, the appearance of coagulation is observed. The sample consists of colonies isolated on an agar medium.
What is coagulase test used for?
The coagulase test is useful for differentiating potentially pathogenic Staphylococci such as Staphylococcus aureus from other Gram positive, catalase-positive cocci.
How do you make rabbit plasma?
a) Preparation of the plasma -Take exactly 10 ml of solvent using a sterile pipette. – Under sterile conditions, add the 10 ml of solvent directly to the vial of freeze-dried rabbit plasma. – Shake gently to ensure dissolution while avoiding the formation of bubbles.
Which medium is used for 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.
What type of plasma is used for coagulase test?
The tube test uses rabbit plasma that has been inoculated with a staphylococcal colony (i.e., Gram-positive cocci which are catalase positive). The tube is then incubated at 37 °C for 1.5 hours.
What type of plasma is used for tube coagulase test?
For tube coagulase tests, colonies of test isolates were re-suspended in 2 ml of citrated sheep or human plasma in sterile glass test-tubes. Since citrate is utilized by enterococci [16], pure colonies of Gram positive, Catalase positive staphylococci (catalase tests preceded coagulase reactions) were used.
What are the 2 types of coagulase test?
The enzyme coagulase, produced by a few of the Staphylococcus species, is a key feature of pathogenic Staph. The enzyme produces coagulation of blood, allowing the organism to “wall ” its infection off from the host’s protective mechanisms rather effectively. There are 2 methods: slide test and tube test.
How do you reconstitute rabbit coagulase plasma?
Reconstitute the Rabbit Coagulase Plasma by adding sterile distilled or deionized water to the vial in the volume indicated on the product label. Gently rotate the vial until the product has completely dissolved. If the prod- uct does not completely dissolve or contains fibrin clots or strands do not use the product.
How do you test for blood clots in rabbit plasma?
Emulsify several isolated colonies of test organism in 1 ml of diluted rabbit plasma* to give a milky suspension. Incubate the tube at 35°C in ambient air or in a water bath for 4 hours. Examine at 1, 2 and 4 hours for clot formation by tilting the tube through 90 °. (Clots may liquefy after their formation)
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.
How do you make a milky suspension of rabbit plasma?
Emulsify several isolated colonies of test organism in 1 ml of diluted rabbit plasma* to give a milky suspension. Incubate the tube at 35°C in ambient air or in a water bath for 4 hours. Examine at 1, 2 and 4 hours for clot formation by tilting the tube through 90 °.