CHAPTER XXVI. 



THE CHOLERA GROUP. 



CHOLERA VIBRIO. 



Vibrio of Finkler and Prior (Vibrio 

 Proteus) . 



Vibrio Metchnikovi. 



Vibrio Massaua. 



Vibrio Tyrogenum (Spirillum Deneke). 



MANY vibrios have been described which possess in common with 

 the cholera vibrio a number of cultural characters. They are all 

 comma-shaped organisms, Gram-negative, possess a terminal flagellum, 

 form no spores or capsules, and liquefy gelatin more or less rapidly. 

 They differ among themselves culturally chiefly with respect to the 

 intensity with which these reactions occur. Some produce nitroso 

 indol in sugar-free culture media, others produce indol only. They 

 may be sharply differentiated from the true cholera vibrio by serum 

 reactions. So far as is known, none of these organisms will agglutinate 

 with a specific cholera immune serum in high dilution, 1 to 2000 to 

 1 to 5000, depending upon the titre. None of these organisms are 

 dissolved by cholera immune serum (Pfeiffer reaction). The true 

 cholera vibrio gives these serum reactions. Most of these organisms 

 have been isolated from water. Even within the group of the true 

 cholera cultures, that is, those which react with a specific cholera 

 immune serum, there appear to be varieties which are distinguishable 

 from the type organism with great difficulty. The principal variants 

 are described below. 



CHOLERA VIBRIO. 



Synonyms. Vibrio cholerae asiaticae, Spirillum cholerae asiaticae, 

 comma bacillus, cholera vibrio. 



Historical. The cholera vibrio was first isolated in pure culture 

 by Koch in 1883. 1 For some years the organism was not universally 

 accepted as the causative agent in Asiatic cholera, and some weight 

 was attached to the frequent isolation of vibrios very similar in mor- 

 phological and cultural characters to the true cholera vibrio from the 

 dejecta of normal individuals. These cholera-like vibrios were not 



1 Deutsch. med. Wchnschr., 1883, 615, 743; 1884, 63, 111, 221, 499, 519; 1885, No. 

 37a; British Med. Jour., 1884, ii, 403, 453. 



