Abstract
Hemolytic strains of staphylococcus producing a varying amount of yellow pigment are found in pyogenic processes, in septicemias, and also in non-suppurative types of dermatitis and on apparently normal skin. The majority of strains from these varied sources cross-agglutinate in monovalent serums. In an attempt to differentiate them by the method of agglutinin absorption an interesting relationship has been brought out which is in accord with the hypothesis of a multiple antigenic composition for such organisms.
Agglutinating sera were made in rabbits and reciprocal agglutinating absorptions carried out. To obtain constant results it was found necessary to use fresh suspensions of standard strength and even so, specific reactions seemed obtainable only in narrow quantitative limits. If too heavy suspensions were used absorption was obtained which was apparently non-specific. This was due probably to adsorption of the anti-bodies by the bacteria, similar to that which can be accomplished by thick finely divided insoluble suspension of many substances. Tentative grouping could be obtained by testing the varied serums in an optimum dilution, but for clear cut results the following technique was found most satisfactory: A series of dilutions of the serum from 1-10 to 1-12,800 was prepared and each dilution absorbed with a standard dose of fresh cocci. After absorption and centrifugation the supernatant fluid was divided into 2 parts and tested for agglutination; one part against the strain used for absorption and the other against the strain used for production of the serum. With completely analogous strains complete absorption appeared at the same dilution, that is, if all the antibodies for the absorbing strain were removed those for the immunizing strain were also removed. Such a reaction, however, was not always reciprocal and a given strain often absorbed all the agglutinin from the serum from another strain when a suspension from this second strain would not remove all the agglutinin from a serum prepared against the first. In reciprocal tests with three strains A, B and C, it was found that:
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