BILE COMPARED WITH LACTOSE BOUILLON 75 



The expense of obtaining bile salts discouraged their use, and 

 it therefore seemed necessary to find a more uniform substance 

 which could be easily obtained. In regard to glucose bouillon 

 Weston and Tarbett (1907) have reported experiments upon 

 the comparison of lactose bile and glucose bouillon in the 

 examination of sixty-three samples of water, showing that 

 although glucose permitted the production of gas from a larger 

 number of samples than bile, yet B. coli could be confirmed from 

 the glucose fermentation tubes in only 13 per cent of these 

 samples. This result was confirmed by a small number of 

 experiments conducted in this laboratory in 1911-1912. 



Members of the Hygienic Laboratory of the U. S. Pubhc 

 Health Service have suggested the use of lactose bouillon and 

 referred to satisfactory results which they have obtained from 

 its use during the past few j^ears. Their suggestion was strength- 

 ened by the report given by Theobald Smith (1895) that 

 Chantemesse and Widal looked upon gas-production in lactose 

 bouillon as conclusive evidence of the presence of B. coli, and 

 by the work of Hall and Nicholls (1914) which showed that if 

 the percentage of lactose added to bile be increased to 15 per 

 cent the productioxi of gas would be more rapid. Organisms of 

 the B. coli group are the only aerobes^ commonly found in water 

 which will ferment lactose with the production of gas. The few 

 anaerobes which might be found to produce gas may be elimin- 

 ated by subsequent transfers to Endo's medium. It was, there- 

 fore, thought practical to substitute this medium for bile. 



When a medium is used in large quantities, as bile usually 

 is, comparative costs become important. Lactose and pep- 

 tone are used in equal quantities in both media. The differ- 

 ence in cost of the two media depends upon the cost of the raw 

 bile in one and the meat extract used in the other. Meat ex- 

 tract at contract price costs approximately three cents for the 

 quantity required for making one hter of nutrient broth. The 



' The Committee on the Standard Methods of Water Analysis, in their report 

 read before the meeting of the American Public Health Association, held at 

 Rochester, N. Y., in September, 1915, defined the B. coli group as including all 

 aerobic bacteria which produce gas in lactose broth. 



