DEHYDRATED CULTURE MEDIA 109 



the rapid cultivation of Mycobacterium tuberculosis. This modification was pre- 

 pared since we considered it to give earlier and more rapid growth than the 

 original Dubos formula, as well as the initiation of growth from inocula contain- 

 ing fewer organisms. This base, when enriched with Bacto-Dubos Medium 

 Serum, will support luxuriant growth of tubercle bacilli from dilute inocula 

 after a short incubation period (within 7-10 days). M. tuberculosis produces 

 a granular growth, settling to the bottom of the tube in this medium. When the 

 base is enriched with Bacto-Dubos Medium Albumin a readily dispersible or 

 diffuse growth is obtained. 



A discussion of liquid media for the cultivation of the tubercle bacilli is given 

 in the description of the medium, Bacto-Dubos Broth Base, (page 105). Media 

 prepared from Bacto-TB Broth Base are recommended for the cultivation and 

 propagation of pure cultures of AI. tuberculosis, and for culturing pathological 

 specimens such as spinal, pleural and peritoneal fluids likely to contain the 

 tubercle bacillus in pure culture. It is also employed for determining the sensi- 

 tivity of M. tuberculosis to antibiotics and other chemotherapeutic agents. Gen- 

 erally, solid media have proven more satisfactory for initial propagation of the 

 organism from specimens. 



The medium may be prepared with or without glycerol. The addition of 

 glycerol enhances the growth of human strains of tubercle bacilli and is not re- 

 quired by bovine or avian strains. Glycerol may be added to the distilled water 

 at the time of rehydrating the medium. The use of Bacto-Glycerol is recom- 

 mended since it has been tested bacteriologically to insure freedom from toxic 

 principles and for suitability for use in this medium. 



To rehydrate the medium, dissolve 2.4 grams Bacto-TB Broth Base in 180 ml. 

 of distilled water or 170 ml. of distilled water containing 10 ml. Bacto-Glycerol. 

 Sterilize in the autoclave for 15 minutes at 15 pounds pressure (121°C.). Cool to 

 below 50° C. and add the contents of one tube Bacto-Dubos Medium Serum 

 (20 ml.) or one tube Bacto-Dubos Medium Albumin (20 ml.) under aseptic 

 conditions. The medium is mixed thoroughly and distributed under aseptic 

 conditions in 16-20 mm. diameter test tubes in 5-7 ml. amounts. The medium is 

 then ready for inoculation. Final reaction of the base and medium prepared as 

 above will be pH 7.0. 



One pound of Bacto-TB Broth Base will make 37.8 liters of medium. 



ij. Exp. Med., 83:409:1946. 



BACTO 



TB BROTH BASE (B374) 

 without Tween 80 



DEHYDRATED 



Bacto-TB Broth Base without Tween 80 has the same formula as Bacto- 

 TB Broth Base except Tween 80 has been omitted. In certain tests to deter- 

 mine the sensitivity of tubercle bacilli to various antibiotics or other bacterio- 

 cidal agents, it may be desirable to omit the Tween 80. There is a possibility that 

 this material present in the medium may influence the sensitivity of the tubercle 

 bacilli to the test substance. 



