Antigenic studies on Micrococcus strains

Induction of resistance with heat-killed compact-type strains of Staphylococcus aureus against challenge with the diffuse variant of the Smith strain of Staphylococcus aureus

Active immunization of mice with high doses of heat-killed and autoclaved vaccine of unencapsulated strains of Staphylococcus aureus, which was grown in brain heart infusion media, protected against challenge with the Smith diffuse strain of Staphylococcus aureus. These organisms were capable of absorbing the protective antibody in rabbit hyperimmune sera prepared with the Smith diffuse strain. Also, mice treated with rabbit hyperimmune sera prepared with these strains (four out of six strains) protected against challenge with the Smith diffuse strain. Protective activities of these rabbit hyperimmune sera were assumed to be essentially identical to the protective antibody induced by the Smith diffuse strain.

Immunological properties of teichoic acids

Images

Serological typing of Staphylococcus epidermidis strains by the serum-soft agar technique

Antisera to five different diffuse forms of Staphylococcus epidermidis were prepared in rabbits as a mean of serological differentiation of S. epidermidis strains. These antisera converted the growth types of the homologous strains from diffuse to compact form in serum-soft agar but did not convert the heterologous strains. The converting activities of the antisera were absorbed out with homologous organisms and not by heterologous strains, indicating the specific serological properties of these strains. Further, the converting activity was absorbable with cell surface substance extracted by sonic oscillation and was not absorbed with cells from which this surface substance had been removed. With these factor sera and the serum-soft agar technique, S. epidermidis strains were differentiated, and it was found that 102 of 116 strains or 87.9% were typable. Within the 102 typable strains, 49 and 53 typed as monovalent and polyvalent, respectively. No correlation between source and strain types of S. epidermidis was found.

Induction of hemolysin synthesis by tranformation in Staphylococcus aureus

A nonhemolytic strain of Staphylococcus aureus was transformed with deoxyribonucleic acid extracted from two hemolytic strains of S. aureus. In each case the hemolysin pattern after transformation was identical to that of the donor strain. However, bacteriophage type, serotypes, and other biological properties of the recipient strain remained unaffected.

Biological and Immunological Properties of Encapsulated Strains of Staphylococcus aureus from Human Sources

Of 875 strains of Staphylococcus aureus isolated from human source clinical specimens, 37 (4.2%) were encapsulated strains. These were all negative for clumping factor and could not be typed with bacteriophages or by serology. Twenty-one of these did not produce any hemolysins, 15 produced alpha hemolysin, 1 produced beta hemolysin, and 1 produced both beta and delta hemolysins. After one or two subcultures, 27 of the encapsulated strains converted to the compact variant form, all became positive for clumping factor, 12 became phage-typable, and 24 became sero-typable. In addition, 7 strains converted from negative to alpha hemolysin production. Comparison of phage- and sero-types did not reveal any relationships. Immunologically, mice challenged with heat-killed encapsulated strains were protected against a challenge infection with the Smith diffuse strain. Protective antibodies in rabbit anti-Smith diffuse strain antisera were removed by adsorption using the encapsulated organisms isolated in this study. The adsorbed sera no longer protected against challenge infection in mice with the Smith diffuse strain. From these results, it appears that the encapsulated strains isolated were immunologically and biologically similar to the classical Smith diffuse strain.