Virulence Of Staphylococcus Aureus Tested By Intracerebral Inoculation Into Mice

When tested by intracerebral injection in mice, a strain of Staphylococcus aureus containing antigen 17 was found to be much more virulent than a variant that lost this antigen and contained antigen 1 in its place. Since 85.7 per cent. of the mice challenged died between 7 and 11 hr after inoculation it is suggested that a toxin was the cause of death.

A standardised test by intracerebral inoculation is considered to be a useful test of virulence in mice. Out of 100 recently isolated coagulase-positive strains assessed by this method, only 18 were considered to be avirulent. The degree of virulence was correlated with the clinical source of the strains.