

BACTERIAL VACCINES 23 



the complement. No free complement is left to combine 

 with those amboceptors that are attached to the bacterial 

 cells. The complex (amboceptor-f complement + organ- 

 ism) that is necessary for bacteriolysis is therefore not 

 provided. 



Serum-Therapy. By repeated injection of animals 

 with gradually increasing doses, sublethal at first, of either 

 the specific toxin or the living culture, a state of gradually 

 increasing resistance is acquired by the animals against 

 the toxin or the microbe. The blood attains an immunis- 

 ing power that is transferable to a new subject. If in- 

 jected into a fresh animal, the blood confers on the latter 

 resistance against the specific infection. The immunising 

 power of such blood-serum comes into action even after 

 infection has already taken place that is to say, the blood- 

 serum has a curative therapeutic action. 



Bacterial Vaccines. The injection of sterilised cultures 

 of certain pathogenic organisms serves to protect against 

 the diseases concerned. Such vaccines may be adminis- 

 tered as prophylactics in anticipation of exposure to the 

 specific infection; or they may be used as therapeutic 

 measures after infection has taken place. Inasmuch 

 as slightly different organisms of the same species may be 

 involved in different cases of an infection, a vaccine is 

 usually made from perhaps ten different strains (poly- 

 valent vaccine). A vaccine is specific i.e., only likely to 

 suppress or cure infection when this is produced by an 

 organism of a character identical with that used for the 

 vaccine. By use of a polyvalent vaccine the probability 

 that the article specific for the infection is used corre- 

 spondingly increases. A vaccine supplied from organisms 

 isolated from previous cases of the disease (or of other 

 diseases due to the same organism) is known as a stock 

 vaccine. If prepared from cases occurring in the same 

 institution or neighbourhood, it is produced from strains 

 of local flora. When infection of a case has already taken 

 place, and the responsible organism is isolated, a vaccine 

 may be prepared from it (autogenous or personal vaccine). 



A description of the preparation of an autogenous vaccine 

 will show the principles employed. The responsible 

 organism is identified by microscopical examination of 

 the material obtained, this being supplemented if possible 

 by cultural and agglutination experiments. It is isolated 



