Abstract
Serological properties were investigated in the unique staphylococcal strains, E 46 and E 97, which are coagulase-negative but deoxyribonuclease-positive, and which had been described in the preceding parts of the present series of papers. They were compared between these strains and typical strains of each of Staphylococcus aureus (E 111 and B 40) and S. epidermidis (E 241 and B 217). The four strains were also described in the same preceding papers. As antigen were used thimerosal-treated cells of each strain for the cross agglutination and the agglutinin absorption tests, and the condensed culture filtrate of each strain or the polysaccharide fraction from the E 46 strain for the precipitin reaction, and the same polysaccharide fraction for the skin test. Antisera were obtained from rabbits immunized with the killed cells mentioned above. The results obtained are as follows.
1) The immunologic tests revealed that both unique staphylococcal strains possessed the same antigenic structure, and that they had a common antigen with both strains of S. aureus, but not with either of the two strains of S. epidermidis.
2) As described in the first report of this series, the unique staphylococcal strains gave rise to diffuse colonies in the serum soft agar using normal rabbit serum or plasma, as well as the E. epidermidis strains did, wheres the S. aureus strains formed compact colonies. In the present similar experiments using such anti-rabbit sera as described previously, all the unique staphylococcal and S. epidermidis strains were converted to such extent as to form compact colonies in the case of their respective homologous antisera, but not in the case of their heterologous antisera, whereas the S. aureus strains were not affected at all either by the homologous or by the heterologous antisera.
Thus, it may be possible to confirm that the unique staphylococcal strains possess identical morphological, biological, and serological attributes and also intermediate properties between the typical strains of S. aureus and S. epidermidis, although they are much closer to the former species than the latter.
