INGREDIENTS OF CULTURE MEDIA 283 



holder, McVeigh and Wilson,^ Mimms and Laskowski,^ Bird, Bressler, Brown, 

 Campbell and Emmett'^ and Laskowski, Mimms and Day.® 

 Bacto-Chicken Pancreas is supplied in 10 gram packages. 



1 A.O.A.C, Seventh Edition: 785: 1950. ^ Arch, of Biochem., 7:287:1945. 



^A.O.A.C, Seventh Edition: 786: 1950, « J. Biol. Chem., 160:^93:1945. 



'The Association of Vitamin Chemists, Inc., ' J. Biol. Chem., 159:631 : 1945. 



Second Edition : 231 :i95i. s j, giol. Chem., 157:731:1945. 

 ^ J. Biol. Chem., 177:117:1949. 



B AGTO-PEN ASE ( B345 ) 



Bacto-Penase is a potent sterile thermolabile biological extract capable of 

 neutralizing the antibiotic properties of all known types of penicillin. It is non- 

 toxic to microorganisms and, therefore, particularly well suited for use in media 

 for culturing bacteria from blood and other body fluids containing penicillin 

 and for estimating penicillin levels in such fluids.^-- "Diagnostic Procedures and 

 Reagents"^ recommend that a penicillin inactivator, penicillinase, be included 

 in media for culturing organisms from blood of patients under penicillin therapy. 

 Bacto-Penase is ideally suited for this purpose. It is also satisfactory for use in the 

 sterility testing of penicillin and products containing penicillin and for ascertain- 

 ing the microbial counts on penicillin-containing products. Bacto-Penase or 

 Bacto-Penase Concentrate is recommended as a penicillinase for use in all official 

 procedures for the sterility testing of penicillin as specified by the U. S. Govern- 

 ment.* Most laboratories prefer to use Bacto-Penase Concentrate in such pro- 

 cedures. 



One ( 1 ) ml. of Bacto-Penase will inactivate 50,000 units or more of penicillin 

 as indicated by the following test procedure: 



Prepare dilutions of Bacto-Penase of 1 : 2, 1 : 3, 1 : 4, 1 : 5, 1 : 6, 1 : 7, 1 : 8, 1 : 9 and 

 1:10 in sterile distilled water. Add 1 ml. of each dilution to a series of test tubes 

 containing 15 ml. of Bacto-Fluid Thioglycollate Medium. Add 1.0 ml. of a solu- 

 tion of penicillin containing 5000 units per ml. to each tube and allow to remain 

 at room temperature for two hours. Inoculate each tube with 1.0 ml. of a 24-hour 

 broth culture of Micrococcus pyogenes var. aureus P209 diluted 1:1000 and 

 incubate at 37°C. for 24 hours. Determine the highest dilution permitting growth 

 in this period and multiply this dilution of Bacto-Penase by 5000. This will give 

 the actual units of penicillin that 1.0 ml. of Bacto-Penase will inactivate. 



M. pyogenes var. aureus P209 will show growth in 18-24 hours in 15 ml. of 

 Bacto-Fluid Thioglycollate Medium or Bacto-Brain Heart Infusion with PAB 

 and Agar containing 50,000 units of penicillin and 1 ml. of Bacto-Penase. Suitable 

 controls show that less than 3 units of penicillin per 15 ml. of medium inhibit 

 growth completely in the absence of Bacto-Penase, and that Bacto-Penase is not 

 inhibitory to the growth of microorganisms. The maximum efficiency of Bacto- 

 Penase against penicillin will be obtained if the reacting substances are contained 

 in small volumes. 



In culturing blood or other body fluids containing penicillin it is recommended 

 that 1 ml. of Bacto-Penase be added to each 100 ml. or less of sterile Bacto- 

 Brain Heart Infusion with PAB or Bacto-Brain Heart Infusion with PAB and 

 Agar. This will assure inactivation of the maximum amount of penicillin that 

 would be present in 10 ml. of blood or other body fluid. A medium so prepared 

 will also inactivate sulfonamides and up to 1000 units of streptomycin introduced 

 with the inoculum. 



The sterility of penicillin is determined by adding the test sample to sterile 

 Bacto-Fluid Thioglycollate Medium containing Bacto-Penase and incubating the 

 tubes at 35-3 7 °C. for 4 days. The test is performed in tubes containing 15 ml. of 



