210 DIFGO MANUAL 



BACTO 



TYROTHRIGIN ASSAY AGAR (B414) 



DEHYDRATED 



Bacto-Tryptone 5 g. 



Bacto-Beef Extract 3 g. 



Bacto-Agar 15 g. 



Bacto-Tyrothrlcin Assay Agar is recommended for carrying stock cultures of 

 streptococcus sp., Lancefield group D, strain No. H69D5 (ATCC ^9854) em- 

 ployed in the assay of tyrothricin according to the procedure given by U. S. 

 Pharmacopeia.^ This medium is also suggested as a solid medium for the culti- 

 vation of a large variety of microorganisms. 



In the assay of tyrothricin the test organism is carried in stock on a Blood Agar 

 prepared by adding 2 per cent sterile defibrinated human, horse or rabbit blood 

 to sterile melted and cooled Tyrothricin Assay Agar. The complete medium is 

 allowed to solidify in a slanted position. If Blood Agar is to be prepared for 

 purposes other than carrying cultures of streptococcus sp., Lancefield group D, 

 strain No. H69D5 for tyrothricin assay, it is suggested that 0.5 per cent sodium 

 chloride be added to the medium to make it isotonic, in order to prevent 

 hemolysis of the blood cells. 



To rehydrate the medium, suspend 23 grams of Bacto-Tyrothricin Assay Agar 

 in 1000 ml. of cold distilled water. Heat to boiling to dissolve the medium com- 

 pletely. Distribute in tubes or flasks and sterilize in the autoclave for 15 minutes 

 at 15 pounds pressure (121°G.). To prepare Blood Agar, cool the sterile melted 

 agar to 45-50° C. and add the desired sterile defibrinated blood under aseptic 

 conditions. Final reaction of the medium will be pH 6.8. 



One pound of Bacto-Tyrothricin Assay Agar will make 19.7 liters of medium. 



1 Pharmacopeia of the United States, XIV Re- 

 vision: 650: 1950. 



BACTO 



POLYMYXIN BASE AGAR (B462) 



DEHYDRATED 



Bacto-Casitone 17 g. 



Bacto-Soytone 3 g. 



Bacto-Dextrose 2.5 g. 



Sodium Chloride 5 g. 



Dipotassium Phosphate 2.5 g. 



Bacto-Agar 20 g. 



Bacto-Polymyxin Base Agar is prepared according to the formula specified 

 by "The Compilation of Tests and Methods of Assay for Antibiotic Drugs,"^ 

 Federal Security Agency, Food and Drug Administration for base layer in the 

 cylinder assay of polymyxin B. This medium is also used for carrying stock cul- 

 tures of the test organism. Brucella bronchiseptica (ATCC ^4617), and pre- 

 paring the inoculum in the polymyxin B. assay. 



To rehydrate the medium, suspend 50 grams Bacto-Polymyxin Base Agar in 

 1000 ml. distilled water and heat to boiling to dissolve the medium completely. 

 Distribute in tubes or flasks and sterilize in the autoclave for 15 minutes at 15 

 pounds pressure (121°C.). Final reaction of the medium will be pH 7.3. 



One pound of Bacto-Polymyxin Base Agar will make 9.1 liters of medium. 



*The Compilation of Tests and Methods of 

 Assay for Antibiotic Drugs. Federal Security 

 Agency, Food and Drugs Administration. 



