52 LABORATORY COURSE IN SERUM STUDY 



LESSON VII 

 PFEIFFER PHENOMENON 



VIRULENT cholera spirilla injected into the peritoneal cavity 

 of a normal guinea pig proceed to multiply rapidly after a pe- 

 riod of about half an hour, and the animal dies usually within 24 

 hours with symptoms of profound intoxication. The same spirilla 

 injected into an animal which has been immunized by previous 

 injections of killed spirilla or of sub-lethal doses of the living 

 microorganisms become granular and in some cases swell, take 

 on globular and vacuolated forms and gradually undergo lysis. 

 The guinea pig in such cases recovers completely from the in- 

 jection. This destruction of invading bacteria by the immune 

 animal was termed by Pfeiffer " bacteriolysis." It has been ob- 

 served with certain of the Gram-negative bacilli such as the 

 typhoid and the dysentery bacillus, but is best observed in 

 cholera. Similar lysis is observed if the spirilla are injected into 

 a normal pig together with serum of an immunized guinea pig or 

 rabbit. 



For this experiment it is necessary to employ a virulent 1 strain 

 of cholera spirilla, since old laboratory cultures do not show the 

 phenomenon sharply and rarely kill the guinea pigs in the con- 

 trols. 



The lethal dose of the particular strain of cholera used for 

 the guinea pigs should be determined roughly before carrying out 

 the experiment. 



It is inadvisable to allow students, except in very small groups, 

 to handle virulent cholera cultures, so that in carrying out this 

 experiment, the preparation of the cholera suspension, the in- 

 jection of the pig and the removal of specimens from the peri- 

 toneum, as described below, should be carried out by the instruc- 

 tor. The smears should be fixed immediately in 10 per cent 

 foimalin, after which they may be distributed to the members of 

 the class for study. 



Two pigs one normal, the other previously immunized with cholera 

 spirilla are intraperitoneally injected with the determined dose, say a 



1 The strain must be recently isolated or one that has been passed through guinea 

 Digs until it will kill in quantities of one loopful of an agar slant. 



