ANTI-STREPTOCOCCIC SERUM 237 



pyogenes, abscess in one case, erysipelas in another, cellu- 

 litis or pyaemia in a third, are attributable partly to real 

 differences in virulence, partly to the site of infection and 

 mode of entrance into the body, partly to real differences 

 existing between different races of streptococci. Strepto- 

 cocci have been described in a number of diseases about 

 which we know little, such as variola, scarlatina (S. 

 scarlatince or conglomeratus), and vaccinia, but it is un- 

 certain what causal relation they bear to these conditions. 

 Strangles, a disease of horses, seems to be due to strepto- 

 cocci. 



Anti-serum. The important lesions due to the strepto- 

 coccus and their grave nature have led to the attempt to 

 prepare an anti-serum, but many and great experimental 

 difficulties have to be overcome to do this. The virulence 

 of the streptococcus has to be increased by passing it 

 through a series of rabbits, and it is only by growing it in 

 serum media that satisfactory cultures for the inoculation 

 of the horses can be prepared. Human serum is the best, 

 but is difficult to obtain ; a mixture of asses' serum and 

 peptone beef-broth comes next. The cultures are grown 

 for about a fortnight and are then inoculated into horses, 

 first killed and then living cultures being used, and after 

 a time the blood acquires anti-microbic properties. It 

 is customary now to make use of a " polyvalent " serum, 

 i.e. one prepared by the injection of many strains of 

 streptococci. The streptococcus anti-serum has been 

 employed in erysipelas, cellulitis, puerperal fever, and 

 pyaemia, in many cases with success. Cheyne suggested 

 its use before operations about the mouth and throat as 

 a preventive of septic pneumonia, but a vaccine would 

 probably be better for this purpose. 



A vaccine prepared by sterilising cultures with heat has 

 been used with benefit in streptococcic infections, which 

 do not run too rapid a course, e.g. infective endocarditis. 



