THE ENDO MEDIUM FOR THE ISOLATION OF B. 

 DYSENTERIAE AND A DOUBLE SUGAR MEDIUM 

 FOR THE DIFFERENTIATION OF B DYSENTERIAE, 

 SHIGA AND FLEXNERi 



I. J. KLIGLER AND J. DEFANDORFER 

 From the Laboratories of the Rockefeller Institute for Medical Research, New York 



Received for publication December 24, 1917 



This paper is based on a study of means of isolating Bacillus 

 dysenteriae from human excreta and polluted soil or water, in 

 which it may be contained. Previous experience (Kligler, 1918) 

 had shown that with respect to sensitiveness to chemicals, 

 the dysenteric group of bacilli approached the Gram positive 

 bacteria; or, in other words, departed from the typhoid and 

 paratyphoid groups. On the other hand, when an enriching 

 medium was employed for cultivation (nutrose, bile, egg), it 

 proved just as favorable to the growth of other intestinal bacteria 

 as to B. dysenteriae. Hence resort was had to a plate medium 

 that would afford colony differentiation and permit at the same 

 time the development of very dehcate strains of the dysentery 

 bacillus. Of the two available media for this purpose, htmus- 

 lactose agar and Endo's medium, the latter presented certain 

 advantages. 



Modified Endo medium. In carrying forward the cultivation 

 on the Endo medium it was discovered that pure cultures of the 

 Shiga dysentery bacillus or cultures in fecal emulsions sometimes 

 gave irregular results. It appeared at first that the fuchsin 

 acted as the inhibitive agent, being more effective against the 

 Shiga bacillus than against the Flexner group of bacilh. In 

 following out this line of experiment, it was determined that the 



1 Work aided by a grant from the International Health Board of the Rocke- 

 feller Foundation. 



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