46 DIFGO MANUAL 



BACTO 



H D BROTH (B443) 



DEHYDRATED 



Bacto-Tryptose 20 g. 



Bacto-Lactose 5 g. 



Sodium Desoxycholate 0.1 g. 



Dipotassium Phosphate 4 g. 



Monopotassium Phosphate 1.5 g. 



Sodium Chloride 5 g. 



Bacto-H D Broth (Hajna Desoxycholate Broth) is recommended as a pre- 

 sumptive and confirmatory medium for coliform bacteria from drinking water, 

 swimming pools, sewage, urine, shell fish and dairy products. This medium is 

 prepared according to the formula given by Hajna,^ using sodium desoxycholate 

 as a selective agent. 



The coliform group as defined by the "Standard Methods for the Examination 

 of Water and Sewage"^ includes all aerobic and facultative anaerobic Gram- 

 negative non-spore-forming bacilli which ferment lactose with gas formation. 

 Leifson^ suggested the use of sodium desoxycholate in Lactose Broth for the de- 

 tection of coliform bacteria. Hajna^ determined that 0.1 g. sodium desoxycholate 

 per liter of Buffered Tryptose Lactose Broth to be optimum for the development 

 of coliforms. This medium proved to be equal or superior to standard Lactose 

 Broth as a presumptive medium and equal or superior to Brilliant Green Bile 2% 

 as a confirmatory medium. 



In comparing the efficiency of the Desoxycholate Broth and standard Lactose 

 Broth using a variety of specimens including market oysters, crab meat, cottage 

 cheese, water samples of all types, swimming pool water samples, milk and urine, 

 2460 tubes showed gas in the H D Broth, all of which confirmed as members of 

 the coliform group; 2811 showed gas in standard Lactose Broth tubes with 2421 

 confirming as coliform by the Brilliant Green Lactose Bile 2% method.^ As a 

 confirmatory medium from 7669 presumptive Lactose Broth tubes, H D Broth 

 gave 7499 confirmations for coliform against 7263 with Brilliant Green Bile 2%.^ 



To rehydrate the medium, dissolve 35.6 grams of Bacto-H D Broth in 1000 ml. 

 distilled water. Distribute in tubes with fermentation vials and sterilize in the 

 autoclave for 15 minutes at 10 pounds pressure (116°G.). Sterilization at 121 °C. 

 is not recommended. Final reaction of the medium will be pH 6.9. 



When the inoculum is larger than 1 ml. per 10 ml. of medium, particular care 

 must be taken to preserve the correct concentration of the ingredients after dilu- 

 tion with the sample. For example if 10 ml. of water are to be added to 10 ml. 

 of medium, the medium should be prepared in double strength. 



One pound of Bacto-H D Broth will make 12.7 liters of medium. 



iPub. Health Lab., 9:77:1951. Water and Sewage, gth Edition: 193: 1946. 



2 Standard Methods for the Examination of 3 j. Path. Bact., 40:581 :i935- 



BACTO 



S F MEDIUM (B315) 



DEHYDRATED 



Bacto-Tryptone 20 g. 



Bacto-Dextrose 5 g. 



Dipotassium Phosphate 4 g. 



Monopotassium Phosphate 1.5 g. 



Sodium Azide 0.5 g. 



Sodium Chloride 5 g. 



Bacto-Brom Gresol Purple 0.032 g. 



