| Coagulase Test |
DESCRIPTION
Coagulase is an enzyme produced by some bacteria that reacts with prothrombin in the blood, forming a complex
named staphylothrombin, which causes blood to clot by converting fibrinogen to fibrin. This mechanism protect
bacteria from phagocytosis.
Frequently coagulase test is used to distinguish between different types of Staphylococcus isolates.
Coagulase is an enzyme produced by some bacteria that reacts with prothrombin in the blood, forming a complex
named staphylothrombin, which causes blood to clot by converting fibrinogen to fibrin. This mechanism protect
bacteria from phagocytosis.
Frequently coagulase test is used to distinguish between different types of Staphylococcus isolates.
PROCEDURE
Harvest blood from a rabbit using EDTA to prevent coagulation. Separate
plasma from blood cells deposit.
Inocculate rabbit plasma with bacteria culture and incubate the tube in a
37 °C incubataor for 3 hours. Examine hourly the clot formation. If
negative then continue incubation up to 24 hours.
Result is positive if the serum coagulates resulting a clot (or a solid block
when the reaction is very intense). Handle the tube with care. The clot
may be fragile and may be disrupted before reading the reaction.
Result is negative if the plasma remains liquid.
Harvest blood from a rabbit using EDTA to prevent coagulation. Separate
plasma from blood cells deposit.
Inocculate rabbit plasma with bacteria culture and incubate the tube in a
37 °C incubataor for 3 hours. Examine hourly the clot formation. If
negative then continue incubation up to 24 hours.
Result is positive if the serum coagulates resulting a clot (or a solid block
when the reaction is very intense). Handle the tube with care. The clot
may be fragile and may be disrupted before reading the reaction.
Result is negative if the plasma remains liquid.
NOTES
Utilization of 2% Na citrate for blood harvesting is no longer recommended. Some bacteria can utilize citrate from
plasma and false positive reactions may appear.
Utilization of 2% Na citrate for blood harvesting is no longer recommended. Some bacteria can utilize citrate from
plasma and false positive reactions may appear.
REFERENCES:
1. H. Raducanescu, V.Bica-Popii,1986. Bacteriologie veterinara, Ed. Ceres, Bucuresti.
2. Margaret Barnett, 1992. Microbiology Laboratory Exercises. Wm. C. Brown Publishers.
1. H. Raducanescu, V.Bica-Popii,1986. Bacteriologie veterinara, Ed. Ceres, Bucuresti.
2. Margaret Barnett, 1992. Microbiology Laboratory Exercises. Wm. C. Brown Publishers.
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(c) Costin Stoica
A demonstration of coagulase test is available in video section.
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