Differentiation of 'Typhoid and Colon Bacilli 66 1 



though for differentiation of typhoid and colon bacilli they 

 cause occasional disappointment. 



Buxton and Coleman* prepare a medium composed of: 



Ox-bile 900 c.c. 



Glycerin 100 c.c. 



Peptone 20 grams 



This was placed in a number of 100 c.c. flasks, sterilized in 

 the Arnold sterilizer, and employed chiefly for blood-culture. 

 The typhoid bacillus grows well in it. 



Jackson f prepares a medium for water examination when 

 typhoid and colon bacilli are suspected. It consists of un- 

 diluted ox-bile to which i per cent, of peptone and i per cent, 

 of lactose are added. It is filled into fermentation-tubes of 

 40 c.c. capacity and sterilized in the Arnold apparatus. If 

 fresh ox-bile cannot be secured, an 1 1 per cent, solution of 

 fresh dry ox-bile can be made; 10 c.c. of suspected water or 

 milk are planted in the tubes of this medium. The contained 

 micro-organisms grow rapidly, typhoid bacilli outgrowing 

 all others, and not fermenting the sugar ; rapid fermentation 

 and copious gas-formation take place if colon bacilli are 

 present. 



An excellent medium suggested by MacConkeyJ has the 

 following composition: 



Agar 1.5 grams 



Sodium taurocholate 0.5 gram 



Peptone 2.0 grams 



Water ico.o c.c. 



It is boiled, clarified, and filtered as usual, then receives an addition 

 of i.o gram of lactose, is tubed, and then sterilized three times on suc- 

 cessive days. 



For determining fermentation by colon bacilli the same 

 investigator advises a broth composed of: 



Sodium taurocholate (pure) 0.5 gram 



Peptone 2.0 grams 



Glucose 0.5 gram 



Water . 100.0 c.c. 



Boil, filter, add sufficient neutral litmus, fill into fermentation-tubes, 

 and sterilize at 100 C. Colon colonies appear red; typhoid, blue. 



* "Journal of Infectious Diseases," 1909, vi, No. 2, p. 194. 

 t "Biological Studies of the Pupils of W. T. Sedgwick," 1906, Uni- 

 versity of Chicago Press. 



t "The Thompson- Yates Laboratory Reports," in, p. 151. 



