Veterinary Clinical Biochemistry and Laboratory Diagnosis-II

COAGULASE TEST

Principle

• The coagulase test is a method to differentiate pathogenic and non-pathogenic strains of Staphylococcus.
• Bacteria that produce coagulase use it as a defense mechanism by clotting the areas of plasma around them, thereby enabling themselves to resist phagocytosis by the host's immune system.

Methodology

• Prepare a 1/10 dilution of plasma in saline and place 0.5 ml of this in a small  tube.
• Inoculate 0.1 ml of a 24 hour broth culture into the plasma.
• Incubate the tube at 37⁰C in a water bath for 3 hours.

Result

• If the organisms are positive for coagulase, the plasma will clot in 1 hour .

Coagulase test

• Positive     : Pathogenic Staphylococci
• Negative   : Non pathogenic Staphylococci