76 APPLIED BACTERIOLOGY FOR NURSES 



cannot possibly be made until after the toxin has had 

 abundant time to combine with the body cells. In the 

 treatment of epidemic cerebrospinal- meningitis spinal 

 injections of specific antimeningococcus serum have 

 reduced the mortality to about one-half that of cases not 

 so treated. 



So far as the bacteriolysins are concerned the clinical 

 results have not been very satisfactory. Investigation 

 has disclosed many difficulties which must still be over- 

 come. In speaking of these sera it is better to use the 

 term "antibacterial," because, after all, when we im- 

 munize an animal against a certain bacterium we do not 

 produce merely a bacteriolysin, but a serum which 

 contains also agglutinins, precipitins, opsonins, and, 

 perhaps, still other antibodies. 



Because of the non-success attending the use of the 

 antibacterial sera, attention has been turned to treatment 

 of bacterial infections bv means of active immunization. 

 Thus, when we inject a horse with diphtheria toxin in 

 order to produce antitoxin we actively immunize; when we 

 inject the antitoxin into a child in order to protect the 

 child against diphtheria we passively immunize. (See 

 page 97.) 



Active immunization consists usually in injecting the 

 patient with small doses of dead bacteria, thus causing the 

 production on his part of the various antibodies already 

 described, and thus bringing about a condition of im- 

 munity. The bacteria are usually grown on agar, in the 

 ordinary way, and, after being washed off into a test-tube 

 containing a little salt solution, are heated for about 

 half an hour to 60 C. in order to kill all the bacteria. 

 Sterility is insured by suitable tests. The suspension is 



