CHOLERA BACTERIA 153 



From Feces. The following technic is recommended: 



1. Examine mucous flakes in stained preparations and 

 hanging drop. 



2. Isolate on agar media at 37 C. 



(a) Plant plates of alkalinized agar and Dieudonne's 

 medium with particles of feces. 



(b) Plant in 50 c.c. peptone solution i c.c. fecal matter. 

 After six hours or longer in the incubator at 37 C. 

 take several loopsful from the surface and plant on 

 several plates Dieudonne's and ordinary alkaline agar. 



(c) Investigate agglutination reaction, using drops from 



isolated colonies and secure pure cultures. 



3. Demonstrate the reaction of Pfeiffer and agglutination 

 with the pure colonies. 



Protective Bacterins. Virulent cultures killed by heat have 

 shown protective power and were used extensively during an 

 epidemic in Japan. 



Haffkine has obtained a great reduction in mortality in 

 cholera regions by the use of anticholera bacterins as a pro- 

 tective measure. 



Serum therapy has not been successful. 



Carriers. In some recent examinations of persons exposed 

 to cholera, carriers of typical cholera vibrio have been found. 

 The vibrio may be found, as in typhoid fever, in the gall- 

 bladder. 



Pfeiffer's Reaction and Agglutination. The serum of an 

 animal (a rabbit) made immune against cholera by the in- 

 jection of sterile or living cultures, intravenously, three times 

 at intervals of a week, has an action against the cholera spiril- 

 lum. It first precipitates the bacteria outof an emulsion, leav- 

 ing a clear liquid (agglutination), and then dissolves the bac- 

 teria (bacteriolytic action), leaving only spheric granules. 

 This action is specific, i. e., the cholera immune sera will 

 affect only cholera vibrio. Such serum is not antitoxic, it 

 is bacteriolytic. For diagnostic purposes an agglutination 

 in dilution of i : 1000 by a serum with an activity of i : 4000 

 is suspicious of cholera. The blood-serum of convalescents 



