Coagulase test

About this test

What is the purpose of the test?  

The purpose of the coagulase test is to determine whether a bacterium produces coagulase , an enzyme capable of coagulating liquid rabbit plasma into a solid clot.

How is coagulase activity determined?  

Coagulase tests are performed using a slide agglutination test, where cells from pure colonies are added to two drops of distilled water and mixed to suspend the cells.  Then, rabbit plasma is added to one of the suspensions to see if coagulase will cause agglutination of the bacteria into visible clots of cells.

What medium is used?  

The culture can be grown on any nutrient medium. 

How is the test performed?  

Fresh colonies of the microbe being tested are mixed with two drops of distilled water placed at opposite ends of a microscope slide.  To one of these cell suspensions, a drop of rabbit plasma is added and mixed.  The other serves as the control.   After several minutes, the cell suspensions are observed for the presence of cell agglutination (clumping), evidence of the presence of the enzyme coagulase. 

What reagents are added?  

Rabbit plasma.

Performing this test in the VUMIE Online lab

To view the coagulase  test in VUMIE Online© Online Lab, complete the following steps:

1. Open the Tests link above the Virtual lab and select the Coagulase Video.

2. Observe the test and interpret the results. If the bacterium possesses coagulase, the rabbit plasma will clot due to the presence of the coagulase enzyme. The normally homogeneous cell suspension will form irregular clots. If coagulase is not produced, the medium will remain homogeneous and lack visible clots.  

3. Record the test result observed.