DEHYDRATED CULTURE MEDIA 103 



ing to the method of Huddleson^ and as given in "Diagnostic Procedures and 

 Reagents."^ 



In the past, it has been considered necessary to have meat extract or meat 

 infusions in culture media for the cultivation of bacteria, except possibly for 

 some of the more easily cultivated strains. It has been shown that many fastidious 

 pathogenic organisms can be isolated and cultivated in media prepared without 

 meat extract, infusions of meat or other enrichment if a suitable peptone is em- 

 ployed. Bacto-Tryptose, in 2 per cent concentration, satisfactorily replaces the 

 usual infusion-peptone portion of many media. Huddleson^ pointed out that the 

 probability of isolating Brucella from human blood is hastened and more certain 

 if the blood be incubated in Bacto-Tryptose Broth. Sodium Citrate in 1 per 

 cent concentration added to the medium serves as an anticoagulant and assists in 

 fixing the complement of the blood specimen. 



The procedure in detail for the isolation of Brucella from human blood is 

 given in the discussion of Bacto-Tryptose Agar on page 111. In a personal com- 

 munication Huddleson recommended that the Tryptose Broth blood culture be 

 incubated in 10 per cent carbon dioxide, rather than 25 per cent as originally 

 specified. 



The addition of 0.1 per cent of agar to Tryptose Broth is highly recommended, 

 if the use of this small amount of agar is not objectionable. Diagnostic Pro- 

 cedures and Reagents^ prefers the use of the Tryptose Broth with the addition 

 of 0.05-0.1 per cent agar for culturing Brucella from whole blood. Growth of 

 aerobes and anaerobes in liquid media is greatly increased by the addition 

 of 0.1 per cent of agar, as was demonstrated by Kitchens^ and by Falk, 

 Bucca, and Simmons.'^ Borman and West^ stated that the addition of 0.05-0.1 per 

 cent of agar to the Tryptose Broth was preferable in primary blood culture for 

 Brucella. 



Schuhardt, Rode, Foster and Oglesby,^ by special techniques, demonstrated 

 that a few of the numerous samples of Bacto-Tryptose which had been in his 

 laboratory exhibited some toxicity for certain Brucella abortus strains used in his 

 laboratory. The particular samples of Bacto-Tryptose possessing this character- 

 istic had absorbed moisture and had undergone chemical change. Schuhardt^ in 

 a discussion of this observation stated that "the ease of neutralization of this toxic 

 factor by blood, serum, agar and other substances tends to make the practical 

 significance of the toxicity relatively minor. We probably would not have en- 

 countered it had we not been doing extensive tests on the in vitro effect of sul- 

 fonamides on Brucella using decimal dilution inocula". The high productivity of 

 Bacto-Tryptose Agar, and Bacto-Tryptose used clinically for the isolation and 

 cultivation of Brucella attests to its value for the primary cultivation of Brucella 

 as well as other fastidious organisms. 



To rehydrate the medium, dissolve 25 grams of Bacto-Tryptose Broth in 1000 

 ml. of distilled water. Distribute in tubes, bottles or flasks and sterilize in the 

 autoclave for 15 minutes at 15 pounds pressure (121°C.). The final reaction of 

 the medium will be pH 7.2. 



For best results Bacto-Tryptose Broth should be freshly prepared. If not used 

 the same day as sterilized, heat in boiling water or flowing steam to remove 

 absorbed oxygen and cool quickly without agitation, just prior to inoculation. 



One pound of Bacto-Tryptose Broth will make 18.1 liters of medium. 



1 Huddleson: Brucellosis in Man and Animals, ^ Diagnostic Procedures and Reagents, 

 14:1939. 3rd Edition: 246: 1 951. 



2 J. Bact., 53:5:1947. e J. Infectious Diseases, 29:390:1921. 

 ^ J. Vet. Research, 11:70:1950. '^ J. Bact., 37:121:1939. 



* Diagnostic Procedures and Reagents, ^ J. Bact., 57:1:1949. 



3rd Edition: 17: 195 1. ^Personal Communication, 1949. 



