1. Add 0.5 ml of Coagulase Plasma to a clean test tube.
2. Add 0.5 ml from a pure broth culture or a large loopful of a pure culture from a nonselective medium.
3. Mix thoroughly to emulsify the test isolate.
4. Incubate at 35-37°C in a water bath or incubator.
5. Observe every 30 minutes for clotting by gently slanting the tube. Do not shake.
6. If no clot is visible after 4 hours, leave in water bath or place in a 35-37°C incubator overnight (24 hours). An optional method is to leave the tubes overnight (up to 24 hours) at 25°C.5