Staphylococcus: coagulase test
Within the family
Micrococcaceae, coagulase positive
Staphylococcus sp. are the
organisms of pathogenic significance. You will see frequent reference to "coagulase positive
Staph." in laboratory reports because of the strong association between coagulase production by
the organisms and their virulence. The coagulase positive
Staphylococcus include
Staphylococcus aureus,
Staphylococcus intermedius, and
Staphylococcus hyicus.
In the coagulase test, a pure culture of bacteria is inoculated into a small amount of human or
rabbit plasma. Coagulase positive
Staphylococcus produce an extracellular enzyme, (coagulase),
which, when mixed with plasma on a slide, triggers the clotting mechanism and causes the plasma to clot.
In this picture, the lower slide shows clotted plasma, while the plasma in the upper slide is smooth and unclotted.
