DEHYDRATED CULTURE MEDIA 203 



growth of these organisms from small inocula. A complete discussion of Bacto- 

 Malt Extract Broth is given on page 242. 



BACTO-PENASE 



Bacto-Penase and Bacto-Penase Concentrate are potent penicillinase prepara- 

 tions recommended for the inactivation of penicillin in the sterility testing of 

 penicillin or penicillin products. A complete discussion of these products are 

 given on pages 283 and 284. 



MEDIA FOR 

 MICROBIOLOGICAL ASSAYS 



MEDIA FOR THE ASSAY OF ANTIBIOTICS 



The Difco dehydrated media described in this section are prepared especially 

 for the assay of the potency of antibiotics. The use of dehydrated media corre- 

 sponding to the specified formula is permitted for the assay of antibiotics accord- 

 ing to the method prescribed by the "Compilation of Regulations for Tests and 

 Methods of Assay and Certification of Antibiotic Drugs," Federal Security 

 Agency, Food and Drug Administration and the United States Pharmacopeia. 

 Included in this section are media conforming to their specifications. 



BACTO 



PENASSAY BROTH (B243) 



DEHYDRATED 



Bacto-Beef Extract 1.5 g. 



Bacto- Yeast Extract 1.5 g, 



Bacto-Peptone 5 g. 



Bacto-Dextrose 1 g. 



Sodium Chloride 3.5 g. 



Dipotassium Phosphate 3.68 g. 



Monopotassium Phosphate 1.32 g. 



Bacto-Penassay Broth duplicates the formula of the medium recommended 

 by Schmidt and Moyer^ for use in the serial dilution method for assaying peni- 

 cillin. It also corresponds to the formula of the broth prescribed in "Tests and 

 Methods of Assay for Antibiotic Drugs,"^ Federal Security Agency, Food and 

 Drug Administration, for the preparation of the inoculum in the cylinder assay 

 of penicillin, or in the tube dilution method of penicillin assay; in the turbi- 

 dimetric assay of streptomycin; for the preparation of the suspension of Sarcina 

 lutea (PCI 1001) in the cylinder assay of aureomycin and chloramphenicol; in 

 the turbidimetric assay of bacitracin. Waksman and Lechevalier^ used Bacto- 

 Penassay Broth for the turbidimetric assay of neomycin with Escherichia coli 

 ^9637 as the test organism. 



Schmidt and Moyer^ used the serial dilution method for assaying ethereal 

 solutions and untreated culture liquor of penicillin as a check on the results 

 obtained by the cylinder plate method. Serial dilution methods may also be used 

 in assaying for penicillin in body fluids of individuals under treatment. 



Essentially the serial dilution methods are based upon determinations of the 



