110 DIFCO MANUAL 



BACTO 



PEIZER TB MEDIUM BASE (B400) 



DEHYDRATED 



Bacto-Beef Extract 3 g. 



Bacto-Gasamino Acids 10 g. 



Bacto-Asparagine 3 g. 



Potato Starch 15 g. 



Ferric Ammonium Citrate 0.1 g. 



Magnesium Sulfate 0.015 g. 



Dipotassium Phosphate 3.5 g. 



Citric Acid 0.1 g. 



Bacto-Agar 15 g. 



Bacto-Peizer TB Medium Base with Bacto-Peizer TB Medium Enrichment is 

 recommended for the isolation and cultivation of Mycobacterium tuberculosis, 

 and for the determination of sensitivity of this organism to therapeutic agents. 

 This base and enrichment are prepared according to the formulae described by 

 Peizer and Schecter.^ 



Media prepared with coagulated egg or egg yolk have generally been con- 

 sidered most satisfactory for the isolation and cultivation of the tubercle bacilli. 

 Peizer and Schecter^ described an agar medium enriched with egg yolk, which 

 gave comparable results with coagulated egg yolk media for initial cultivation of 

 the tubercle bacilli from specimens. The medium also gave an early and luxuri- 

 ant growth with satisfactory inhibition of commensal organisms. The medium 

 consists of an agar base to which is added an enrichment composed of egg yolk, 

 glycerol, and dextrose and with malachite green as a selective agent. The basal 

 medium has been prepared in dehydrated form and the enrichment supplied 

 ready for addition to the sterile rehydrated agar base. 



The ease of preparation of the complete medium from Bacto-Peizer TB 

 Medium Base and Bacto-Peizer TB Medium Enrichment in amounts as re- 

 quired, its high nutritional value and its selectivity make it ideally suited for 

 the isolation of the tubercle bacilli from clinical specimens. In addition, the 

 medium may be used for determining the sensitivity of the tubercle bacillus to 

 therapeutic agents. When used for sensitivity testing, the complete medium is 

 poured either into sterile petri dishes or wide-mouth bottles and allowed to 

 solidify. The medium is heavily inoculated by smearing a suspension of the organ- 

 ism over the surface to produce a mass growth. Treated specimens showing a 

 Gaffky of III or more may also be smeared in a similar manner for testing the 

 sensitivity of the organisms from primary culture. Bacto-Sensitivity Disks contain- 

 ing 1, 10 and 100 meg. dihydrostreptomycin are then placed on the inoculated 

 medium. The plates or bottles are sealed and incubated. Observations are made 

 for growth of the organism and size of the zone of inhibition of growth around 

 the disks. See Bacto-Sensitivity Disks (p. 335) for complete discussion of this 

 technique. 



Peizer, Widelock and Schecter^ used this basal medium in testing the sensi- 

 tivity of the tubercle bacillus to streptomycin. In their method the streptomycin 

 was included in the enrichment. 



To rehydrate the medium suspend 49.8 grams Bacto-Peizer TB Medium Base 

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

 pletely. Distribute in 100 ml. amounts and sterilize in the autoclave for 15 min- 

 utes at 15 pounds pressure (121°G.). Cool to 45-50° C. and add the contents of 

 one bottle of Bacto-Peizer TB Medium Enrichment to 100 ml. of the sterile 

 medium. Mix well, avoiding the formation of bubbles. Distribute in sterile tubes 



