Staphylococcal coagulase; mode of action and antigenicity.

Different strains of staphylococci vary in ability to produce free coagulase. Methods are given for the selection of suitable strains and for the production and concentration of coagulase from one of them. Of animal plasmas examined, cow, sheep, dog, guinea-pig and mouse showed a relative deficiency in coagulase activator, while plasma of man, monkey, horse, cat, pig, fowl and rabbit contained the most. Coagulase activator resembles prothrombin closely in physical properties such as thermolability, behaviour during salting out and removal by adsorbents. They are both partly lost in blood clotting and in dicumarol poisoning, but while prothrombin is apparently removed from plasma by repeated Seitz filtration there is no loss of activator. The question of probable identity is discussed. Antibody to coagulase is present in the sera of many normal individuals and in those suffering from chronic staphylococcal infections. The intramuscular injection of coagulase adsorbed on aluminium phosphate produces similar antibodies in the sera of rabbits.