Studies on staphylococcus aureus with reference to coagulase activity

As observed in these studies, mice in the age range of 6-17 days of age were more susceptible to the injection of staphylococcal supernatants than were older mice. Freezing and thawing the storage of a staphylococcal broth culture at -26° C for seven months did not affect the coagulase titers nor the toxic activity of this culture. It was observed that filtration of staphylococcal broth cultures through Seitz and Mandler filters removed coagulase, but did not affect the toxic activity of these cultures. Millipore filtration did not remove coagulase. Prolonged incubation of Staph. aureaus cultures in the present of increased carbon dioxide favored the production of toxin rather that coagulase. Lethality for suckling was sue to the presence of staphylococcal exotoxin in the cultures and in cell free filtrates rather than coagulase. In addition, cell free filtrates were more lethal than were the cultures which contained organisms. Exposure to boiling temperature of cell free filtrates, prepared from cultures of Staph. aureaus strains 15 and 17, did not destroy the toxic activity of these filtrates as it did with the filtrates of strains 5 and 13. The results obtained with strain 17, a turkey isolate, resembled those of the human strain 15. Cell free filtrates of both strains were quite toxic; however, the toxins of strain 15 appeared to be more heat stable than those of strain 17. No significant immunological difference was shown between the heat labile and the heat stable fractions of staphylococcal exotoxin. In addition, mice injected with a mixture of cell free filtrates plus homologous or heterologous antiserm were not protected from the toxic activity of these filtrates. A positive coagulase test was not obtained with a suspension of Staph. aureus strain 15 heated at 56°C for 75 minutes. However, this treatment did not destroy the ability of this organism to produce coagulase. In the experiment to determine if coagulase in produced in vivo, coagulase could not be detected in the supernatant fluid of a suspension of ground mouse muscle tissue.