DEHYDRATED CULTURE MEDIA 101 



Bacto-Tryptose Phosphate Broth is a liquid peptone medium prepared without 

 an infusion of meat, recommended for the cultivation of streptococci, pneumo- 

 cocci, meningococci and other organisms generally considered difficult to culti- 

 vate. This medium is especially adapted for blood culture work. A procedure 

 frequently used for this purpose is to add as much as 10 ml. blood specimen to 

 150 ml. of sterile Tryptose Phosphate Broth contained in a 300 ml. Erlenmeyer 

 flask or bottle. Inoculated flasks are incubated at 37° G. and are observed at in- 

 tervals for bacterial growth. When growth occurs in the flasks, transfers are 

 made to Blood Agar or other suitable media for isolation and identification, 

 according to usual practice. 



The addition of 0.1-0.2 per cent Bacto-Agar to Tryptose Phosphate Broth 

 improves the productivity of the medium for most purposes. The advantages of 

 a medium with a low agar concentration is discussed fully under Bacto-Brain 

 Heart Infusion, page 77. In the "Standard Methods for the Examination of 

 Dairy Products,"^ 0.1 per cent agar is included in the formula for Tryptose Phos- 

 phate Agar Broth as used in the isolation of pathogenic bacteria from cheese. 

 "Diagnostic Procedures and Reagents"- of the American Public Health Associa- 

 tion include the addition of 0.1-0.2 per cent agar in the formula of Tryptose 

 Phosphate Broth. 



Newman^ in a study of the detection of food poisoning attributable to dairy 

 products, used Tryptose Phosphate Broth to which was added 0.1 per cent agar 

 and 1 :2500 sodium azide for the cultivation of streptococci. An incubation tem- 

 perature of 37 °C. was used with this medium. Bacto-Tryptose Phosphate Broth 

 is recommended for use in the tube dilution method of testing the sensitivity of 

 microorganisms to antibiotics. Waisbren, Carr and Dunnett* showed that Bacto- 

 Tryptose Phosphate Broth, Bacto-Dextrose Broth or Bacto-Nutrient Broth were 

 suitable media for comparative sensitivity test studies while a medium contain- 

 ing a soy bean peptone inhibited the action of Neomycin, Aureomycin, Terra- 

 mycin and Polymyxin against the test organism. 



To rehydrate the medium, dissolve 29.5 grams of Bacto-Tryptose Phosphate 

 Broth in 1000 ml. distilled water. Distribute in tubes or flasks. For blood culture 

 work dispense in 150 ml. quantities in 300 ml. Erlenmeyer flasks or bottles. The 

 medium is sterilized in the autoclave for 15 minutes at 15 pounds pressure 

 (121°C.). The final reaction of the medium will be pH 7.3. 



If the medium is not used immediately after preparation, it should be heated 

 in the autoclave or in a boiling water bath in order to drive off dissolved oxygen, 

 and should then be cooled to 37°G. without agitation, just prior to inoculation. 



One pound of Bacto-Tryptose Phosphate Broth will make 15.3 liters of 

 medium. 



1 Standard Methods for the Examination * J. Milk and Food Tech., 13:226:1950. 

 of Dairy Products, 9th Edition: 165:1948. * Am. J. Clin. Path., 21:884:1951. 



2 Diagnostic Procedures and Reagents, 

 3rd Edition: 16: 1950. 



BACTO 



DEXTROSE BROTH (B63) 



DEHYDRATED 



Bacto-Beef Extract 3 g. 



Bacto-Tryptose 10 g. 



Bacto-Dextrose 5 g. 



Sodium Chloride 5 g. 



Bacto-Dextrose Broth is recommended as a liquid enrichment medium for the 

 isolation of many bacteria. It is a superior medium for the cultivation of organ- 



