DEHYDRATED CULTURE MEDIA 51 



tion of acid and turbidity (growth) in an azide presumptive broth after incuba- 

 tion at 45 °C. is considered positive presumptive evidence for the presence of 

 Enterococci. The positive presumptive tests are then confirmed by inoculating a 

 slant-broth combination prepared with an azide agar medium overlaid with a 

 salt-azide-penicillin broth. Pinpoint colonies on the slant, growth sediment in the 

 broth, the presence of Gram-positive ovoid streptococci in the broth, and a nega- 

 tive catalase test is considered confirmed positive evidence of the presence of 

 Enterococci. 



To rehydrate the medium (single strength) dissolve 15.4 grams Bacto-Entero- 

 cocci Presumptive Broth in 1000 ml. of distilled water. Tube in 8 ml. amounts 

 and sterilize in the autoclave for 15 minutes at 15 pounds pressure (121°G.). The 

 concentrated or 5 strength presumptive enrichment broth is prepared by dis- 

 solving 77 grams of Bacto-Enterococci Presumptive Broth in 1000 ml. distilled 

 water. Inocula of 1 loop to 2 ml. are used for 8 ml. tube of the single strength 

 medium. The 5 times strength medium is distributed in 2 ml. amounts and fol- 

 lowing sterilization as above, is inoculated with 10 ml. of sample per tube. The 

 final reaction of the medium is pH 8.4. 



One pound of Bacto-Enterococci Presumptive Broth will make 29.4 liters of 

 medium. 



1 Commercial Fisheries Leaflet TLa, November, 1946. 



BACTO 



ENTEROCOCCI CONFIRMATORY AGAR (B301) 



DEHYDRATED 



Bacto-Tryptone 5 g. 



Bacto-Yeast Extract 5 g. 



Bacto-Dextrose 5 g. 



Sodium Azide 0.4 g. 



Bacto-Agar 15 g. 



Bacto-Methylene Blue 0.01 g. 



A discussion of the use of this medium is given above under Bacto-Enterococci 

 Presumptive Broth. 



To rehydrate the medium, suspend 30.4 grams Bacto-Enterococci Confirma- 

 tory Agar in 1000 ml. of cold distilled water. Heat to boiling to dissolve the me- 

 dium completely and distribute in tubes. Sterilize in the autoclave for 15 minutes at 

 15 pounds pressure (121°C.). The medium is allowed to cool in a slanted posi- 

 tion. The final reaction of the medium is pH 8.0. 



One pound of Bacto-Enterococci Confirmatory Agar will make 14.9 liters of 

 medium. 



