32 CULTURE MEDIA 



i% of peptone. Conradi's medium is ox bile containing 10% of glycerine and 2% 

 of peptone. This is the medium for blood cultures in typhoid, etc. 



The bile lactose medium now used in water analysis is made by adding i% of 

 lactose to ox bile and tubing in fermentation tubes. As a substitute for fresh bile 

 one may use a 15 to 20% solution of a good quality of inspissated ox gall (Pel Bovis 

 Purincatum). A liver bouillon made by using 500 grams of finely divided beef liver 

 in 1000 c.c. of water with i% peptone, and prepared as for meat infusion broth, is a 

 good substitute for bile. 



RECTOR'S BILE LACTOSE NEUTRAL RED MEDIUM 



This is recommended in the isolation of the colon bacillus as superior to lactose 

 litmus agar. It consists of 10% of dried ox bile, i% of peptone, and i>% agar. 

 After the medium is filtered and tubed we add i% of lactose and i% of a i-ioo 

 neutral red solution. Colon colonies have a distinct purplish red zone. Further- 

 more the bile inhibits the growth of many organisms which give pink colonies on 

 lactose litmus agar. MacConkeys' bile salt medium contains %% oi sodium 

 taurocholate and is colored with neutral red. 



THALMAN'S MEDIUM FOR THE GONOCOCCUS 



Five hundred grams of lean, finely minced beef are placed in 1000 c.c. of distilled 

 water and allowed to stand over night in an ice box. It is then filtered and the fil- 

 trate made up to 1000 c.c. with distilled water. To 100 c.c. of the beef juice add 

 iM grams of agar, and boil for 15 minutes. Then add 2 grams of glucose, and bring 

 the reaction to plus 0.6 by addition of N/i NaOH. Tube, sterilize, slant, and in- 

 cubate over night. No peptone or salt is required. We now use Vedder's starch 

 agar. 



PETROFF'S TUBERCLE BACILLUS MEDIUM 



This is a remarkably valuable medium for isolating tubercle bacilli from sputum or 

 pus directly. Fresh sputum shouW be used and for destruction of contaminating 

 organisms it should be shaken up with an equal amount of 3% NaOH solution and 

 left in the incubator for one or two hours. Neutralize with N/i HC1, using litmus 

 paper, and centrifugalize. Take up sediment and smear out on slants of the 

 following medium. 



Treat 500 grams of chopped up meat with 500 c.c. of 15% glycerine solution. Keep 

 in ice chest twenty-four hours and filter through gauze. Sterilize the shells of eggs 

 by immersion in 70% alcohol for ten minutes or by dipping them in boiling water 

 for five seconds or so. Mix white and yolk of these eggs in a sterile mortar and add 

 an equal volume of the glycerine meat infusion which should have added to it before 

 mixing i c.c. of i% alcoholic solution of gentian violet to each 100 c.c. of the 

 glycerine meat infusion. 



Should one be culturing bovine strains the glycerine should be omitted from the 

 meat infusion but the gentian violet (1-10,000) added. Put 3 to 4 c.c. of this me- 

 dium in test-tubes and inspissate as slants at 85C. until the medium is solidified. 





