BACTERIAL VACCINES 213 



in cases of staphylococcus aureus bacteremia, from infected wounds, from 

 abscesses, from the throat in cases of staphylococcus, tonsillitis, etc. 



These various strains are cultivated on plain agar, suspended in salt solution, 

 mixed and sterilized in the water bath at 6oC. to 8oC. from 30 minutes to i 

 hour. 



Staphylococcus vaccines are employed to fortify natural immunity and to 

 combat staphylococcus infections. The average initial dose is from 50,000,000 

 to 100,000,000. 



Staphylococcus albus and citrus vaccines are made in the same way; the 

 same is true of streptococcus and pneumococcus except that these two are best 

 cultivated on blood-agar. The average dose of all is the same. 



Vaccines of any of these cocci seldom produce any marked exaltation of 

 immunity when given to healthy persons; they do not as a rule conspicuously 

 modify or curtail acute infections, their chief value is in the treatment of sub- 

 acute and chronic infections. 



There are innumerable strains of staphylococci that are indistinguishable 

 but differ in that a vaccine made from one does not stimulate antibody forma- 

 tion or immunity to the others. The same is true of streptococci and pneumo- 

 cocci. Therefore, autogenous vaccines are very much superior to stock vac- 

 cines in the treatment of such infections. 



SENSITIZED VACCINES 



Sensitized vaccines are prepared by cultivating the organism on its appro- 

 priate medium, washing off the growth with sterile salt solution, shaking the 

 suspension to break up clumps and counting the number of bacteria per cubic 

 centimeter as previously described. The suspension is then centrifugalized at 

 high speed and when the bacteria have been precipitated the supernatant salt 

 solution is pipetted off and discarded. The bacteria are mixed with the serum 

 of an animal immunized against the same organism. This mixture is incubated 

 at 37C. for 24 hours and then centrifugalized until bacteria precipitate. The 

 serum is syphoned off and discarded. The bacteria are washed in several 

 changes of normal salt solution to rid them of serum. They are mixed with 

 sufficient salt solution to make a suspension containing the desired amount of 

 bacteria per cubic centimeter; and are then sterilized in a water bath at S5C. 

 to 6oC. for y% hour. 



This sensitization, when successfully carried out, is said to prevent or mini- 

 mize undesirable reactions following the injection of the vaccine, to prevent the 

 occurrence of a negative phase to permit the administration of larger doses and 

 repetition of doses at shorter intervals and to produce a higher degree of im- 

 munity than it is possible to secure with non-sensitized vaccines. 



TUBERCULIN 



Tuberculin is used by some in the treatment and in the diagnosis of 

 tuberculosis. 



From among the various tuberculins, the selection of one for use in the treat- 



