Plate method for the determination of the normal serum bacteriostatic activity against staphylococci.

The growth of 100 staphylococcal strains in normal rabbit serum was studied. Determinations were carried out by the tube method previously described and by a new plate method, and the results agreed in both cases. The strains of staphylococci used differed in the production of bound coagulase, clumping factor, and staphylokinase, and exhibited different phage patterns. Their multiplication in serum was not dependent on any of the above-mentioned characteristics. The newly elaborated plate test is characterized by easy and quick performance and allows for the determination of 25 to 36 strains on one Petri plate.