Coagulase

In microbiology, the coagulase reaction of the distinction between pathogenic and (usually) non-pathogenic staphylococci serves. The pathogenic staphylococci ( eg Staphylococcus aureus) are koagulasepositiv ( produce coagulase ), the (mostly) non-pathogenic staphylococci ( eg Staphylococcus epidermidis ) are koagulasenegativ. In order to investigate which kind is present, the bacteria are mixed with fibrinogenhaltigem plasma. Will be provided by the bacterium coagulase, this leads to a clotting of fibrinogen, ie it form lumps ( fibrin).

The word implies a coagulase enzymatic activity. The term is, however, emerged at a time when you could not perform a differentiation in terms of enzymatic activity. Thus, the coagulase enzyme is not in the proper sense, but only an activator of prothrombin ( analogous to factors V and X, and calcium ions in blood clotting ). It via a conformational change in activation of thrombin, which then provides for a precipitation of fibrinogen to fibrin.

The pathogenicity of coagulase arises from the fact that the bacterium is wetted when it enters the body through the coagulase (and also the clumping factor A) with a protective layer of endogenous proteins. These proteins hide the bacterium before the body's immune system and consequently make its elimination.

Evidence of Plasmakoagulase is time consuming (about 24 h), so that one uses the simpler proof of the clumping factor. The clumping factor A, as opposed to the secreted Plasmakoagulase, a cell wall- bound protein which directly binds to fibrinogen. The physiological function is analogous to the Plasmakoagulase.