INTESTINAL OR COL*ON-TYPHOID GROUP 283 



B. dysenterice, however, is non-motile. Spores and capsules are 

 not produced. It stains uniformly and is gram-negative. 



Isolation and Culture. The organism may be isolat'ed directly 

 from the dejecta by plating. The cultural characters in general 

 closely resemble those of B. typhosus. Milk is rendered perma- 

 nently alkaline, however. 1 



Physiology. The physiologic characters of B. dysenterice 

 closely resemble those of B. typhosus. The ability to produce 

 acid in solutions of various carbohydrates and of the related 

 alcohols is used as a means of differentiation of the varieties. 

 Otho listed some fifteen different types by this means. A more 

 conservative and valuable classification is that of Hiss, as modified 

 by Shiga: 



Variety ACID PRODUCED FROM 



B. dysenterice. Mannite. Maltose. Saccharose. Dextrose. 



I. Shiga, type I + 



II. Park-Hiss type 4- 4- 



III. Flexner-Strong type 4- 4- 4- 



IV. Harris-Wollstein type 4- + + + 



V. Shiga, type II * 4-4-4- 



It is believed that type I. is the most virulent. Types III. 

 and IV. are found frequently in summer diarrhea of infants. 



Pathogenesis. Experimental Evidence. The belief that the 

 varieties of B. dysenterice are the more important etiologic factors 

 in the disease is based upon the following facts: 



1. This -organism in some one of its varieties has been shown 

 to be present with great constancy in the patients' excreta. 



2. Injections of the organisms and their products kill laboratory 

 animals, particularly rabbits, although typical dysentery is not 

 readily induced by feeding experiments. 



3. The blood-serum of a patient will, in general, agglutinate 

 in high dilution the strain isolated from the feces. 



4. An antiserum has been successfully used in the prevention 

 and cure of the disease. 



Character of Disease and Lesions Produced. The intestine, 



particularly the colon, is inflamed and is sometimes ulcerated, and 



may even show diphtheritic necrosis. With the exception of this 



there is little that is characteristic of the disease. Unlike the 



1 Initial acidity followed by permanent alkalinity. 



