Extraction of a compact colony-forming active substance from Staphylococcus aureus strains

Isolation of a serologically different compact-colony-forming active substance from strains of Staphylococcus aureus

To observe the possible serological heterogeneity of compact-colony-forming active substance (CCFAS), heat-killed vaccines were prepared by two strains of Staphylococcus aureus, strains SMU 1-46 and SMU 7931, cultured in 0.03 M trishydrochloride-buffered brain heart infusion, pH 8.4. After immunization with the vaccine in rabbits, antibody responses were observed during a period of six weeks after the immunization either by homologous and heterologous organisms using alkaline serum-soft agar technique. The results showed that remarkable antibody production was shown only against homologous strain, but not against heterologous strain. The antibodies were absorbed out only with highly purified preparation of CCFAS extracted from homologous strain and not with heterologous CCFAS. Differences of the major chemical composition of the substances showed that highly purified CCFAS extracted from strain SMU 7931 contained 2.84 and 2.04 times higher amounts of galactose and 2-amino-2-deoxy-D-galacturonic acid than those of CCFAS obtained from strain SMU 1-46.

Comparison of compact colony-forming activity and paracoagulation activity of strains of Staphylococcus aureus in serum and plasmas of various animals

Using 20 strains of Staphylococcus aureus isolated from clinical specimens, the compact colony-forming activity (CCFA) in serum-soft agar (SSA) in sera from various animals and the paracoagulation (PC) activity of the compact colony-forming active substance (CCFAS) extracted from these strains were investigated. The results of this comparative study revealed that the CCFA and PC of S. aureus for sera from various animals in SSA were different, not only among different strains but also in the same strains. In addition, the effect of galactose and calcium ions on the PC activity of these strains in experiments employing human fibrinogen permitted the recognition of these groups of S. aureus strains. In one group, PC activity was decreased by galactose but unaffected by calcium ions, in the second group PC activity was unaffected by galactose but increased by calcium ions, while in the third group it was unaffected by both. These results suggest the possibility of heterogeneity of CCFA among different strains of S. aureus.

Mechanisms of resistance of staphylococci grown in plasma to polymorph bactericidins

The mechanisms whereby staphylococcal strains grown in plasma assume increased resistance to polymorph bactericidins were investigated. Observations reported here showed that cultural conditions could determine the path of conversion to resistance. Staphylococcal strains and mutants lacking either free coagulase or clumping factor or both all showed enhanced resistance after 10 h incubation in plasma proteins, thus giving no clear indication that these factors were involved in the interactions. In fact, prolonged incubation in bovine serum albumin (22 h) and ordinary broth medium (24 h) also resulted in increased resistance. A distinction between staphylococcal factors interacting specifically with plasma proteins and such non-specific conversions was obtained in two different ways. Stripping of a hypothetical surface protein by treatment with trypsin or 2 M potassium bromide rendered plasma- but not 24 h-broth organisms susceptible, indicating protein coating of plasma-grown organisms. Also free coagulase-positive strains and mutants incubated in plasma for 30 min were converted while those lacking both or possessing clumping factor alone were not. It therefore appears that one of the mechanisms of acquiring resistance involves a rapid interaction between staphylococcal-free coagulase and fibrinogen, resulting in the deposition of fibrin or fibrin derivatives on the bacterial surface.

Comparison of the reactions of the compact-colony forming active substance (CCFAS) to the clumping-factor reaction in a strain of Staphylococcus aureus with animal plasma

Plasma was used from rat, mouse, guinea pig, rabbit, dog, cat, sheep, goat, monkey, horse, pig, cow, fox, mink, porpoise, deer, manatee, seal, elephant, raccoon, pigeon, macaw, and humans; clotting time and gel formation activities by the compact-colony forming active substance (CCFAS) extracted from a strain of Staphylococcus aureus and relative staphylococcal clumping factor reaction were determined. Experimental results showed that every plasma was clotted and gel formation of plasma was observed by the CCFAS, however, although it was shown by the other plasmas, no clumping-factor reaction was observed with plasma from guinea pig, goat, and elephant.

Comparison of three blood-clotting substances in Staphylococcus aureus strains

Besides the two well-known blood-clotting substances, coagulase and clumping factor, a third one has been identified from the staphylococci which is a cell surface polysaccharide, is alkali stable, and induces compact-colony formation in serum soft agar. Using some 97 clinical strains of Staphylococcus aureus, we found that in production and activity the substances were distinctly different.