252 PASSIVE IMMUNIZATION 



Regarding the value of the serum in other streptococcus infections, 

 too little is as yet known to warrant any definite conclusions. Here 

 also is a large field for the expert, and until it is tilled by him the 

 results can hardly be expected to be what they should be. As I have 

 suggested, the best results may here be expected from serum treat- 

 ment and vaccine treatment conjointly. 



PNEUMOCOCCUS INFECTIONS 



While the results which have been hitherto obtained in the serum 

 treatment of pneumococcus pneumonia have been rather disappoint- 

 ing, Neufeld and Handel have recently pointed out that this may 

 have been due in part to the administration of sera of too low a titer 

 and of insufficient amounts, in part to the administration by the 

 subcutaneous route, and in part to the use of sera which did not 

 correspond to the same strain as the infecting organism. The same 

 observers could show that the so-called polyvalent sera of commerce 

 were in reality not truly polyvalent, and possessed protective value 

 only against a certain group of pneumococcus strains, while they 

 were of no avail against other types. They emphasize that no cura- 

 tive properties can be expected from a given serum unless this is 

 homologous for the type that is causing the infection. It will accord- 

 ingly be necessary to resume the serum treatment of pneumonia 

 from this standpoint, and to establish the type of the organism in 

 every case before an ultimate verdict upon the subject can be 

 reached. 



A serum which possesses a high degree of protective as well as 

 curative value against the common strains of pneumococci, in the 

 animal experiment, is at present prepared under Neufeld's direction 

 by the Serum Institute of Saxony, and may be recommended for 

 use in infections with the corresponding strains. Its titer is such 

 that 1 c.c. will protect 5000 grams of body weight (tested against 

 white mice weighing from 18 to 20 grams) against 0.1 to 0.0001 c.c. 

 of a pneumococcus bouillon culture, the fatal dose being 0.000001 

 or less. Neufeld and Handel point out that it is essential to test 

 out the serum against large or medium doses of the organism as the 

 values obtained in the case of small doses do not apply to correspond- 

 ing multiples. Of a serum, for example which would protect in a 



