268 IMMUNOLOGICAL METHODS OF DIAGNOSIS 



BACTEEIOLYTIC REACTIONS 



It will be recalled that Pfeiffer pointed out that cholera vibrios, 

 when introduced into the peritoneal cavity of cholera-immune guinea- 

 pigs, are there rapidly destroyed through the agency of the normal 

 complement of the animal and the bacteriolytic amboceptor which 

 has been produced in consequence of immunization. The principle 

 underlying this reaction has been recommended for the diagnosis 

 of both cholera and typhoid fever, but is at present only utilized 

 in connection with the former malady, whereas owing to its greater 

 simplicity, the agglutination test is almost exclusively employed in 

 typhoid fever. This latter test, as we have already seen, is for 

 technical reasons inapplicable in the diagnosis of cholera. 



As in the case of the agglutination test, Pfeiffer's reaction also 

 can be utilized either for the purpose of identifying the organism 

 in question, or in searching for the corresponding amboceptor in 

 the serum of a patient. 



In the first instance the organism under consideration is suspended 

 in cholera immune serum, and the mixture injected into the peritoneal 

 cavity of a guinea-pig, when the prompt occurrence of bacteriolysis 

 will indicate that the organism was actually the cholera vibrio. In 

 the second case, the serum to be tested is inoculated with cholera 

 vibrios, and likewise injected into a guinea-pig, when the occurrence 

 of bacteriolysis will prove that the serum contained anticholera 

 amboceptors and was hence derived from an individual who must 

 recently have passed through an attack of the illness in question. 



It goes without saying, of course, that serum and organisms must 

 in both instances be combined in certain definite proportions, to 

 which end the following procedure may be employed, as recom- 

 mended by the Prussian Institute for Infectious Diseases. 



1. Pfeiffer's Test as Applied to the Identification of Cholera Vibrios. 

 For this purpose an anticholera rabbit serum should be available 

 which should be of such strength at least that 0.0002 gram will cause 

 the complete destruction of an oese ( = 2 milligrams) of an eighteen- 

 hour-old agar culture of the cholera vibrio within one hour after 

 injection into the peritoneal cavity of a guinea-pig. 



One pig (A) is then injected with five times the titer dose of the 

 immune serum, i. e., 1 milligram together with one oese ( = 2 milli- 



