DEHYDRATED CULTURE MEDIA 173 



BACTO 



UREA AGAR BASE CONCENTRATE (B284) 



(Filter Sterilized Solution) 



Bacto-Urea Agar Base is also supplied in a filter sterilized concentrated solu- 

 tion as Bacto-Urea Agar Base Concentrate. The dehydrated medium is recom- 

 mended for those laboratories using large amounts of medium and equipped with 

 filter sterilizing apparatus. For laboratories requiring only small amounts of 

 medium Bacto-Urea Agar Base Concentrate is recommended. 



Bacto-Urea Agar Base Concentrate is a filter sterilized concentrated solution 

 of Bacto-Urea Agar Base, 10 ml. being sufficient for the preparation of 100 ml. 

 final medium. It is especially recommended for use by those laboratories desiring 

 to save time, or requiring smaller quantities of medium. 



To prepare the medium from Bacto-Urea Agar Base Concentrate, dissolve 1.5 

 grams of Bacto-Agar in 90 ml. distilled water by boiling. Sterilize in the autoclave 

 for 15 minutes at 15 pounds pressure (121°C.). Cool to 50-55°C. and add the 

 contents of one tube of Bacto-Urea Agar Base Concentrate (10 ml.), under 

 aseptic conditions. Mix thoroughly and tube as indicated above. 



One tube of Bacto-Urea Agar Base Concentrate will make 100 ml. of complete 

 medium. 



BACTO 

 S I M MEDIUM (B271) 



DEHYDRATED 



Bacto-Beef Extract 3 g. 



Bacto-Peptone 30 g. 



Peptonized Iron, Difco 0.2 g. 



Sodium Thiosulfate 0.025 g. 



Bacto-Agar 3 g. 



Bacto-S I M Medium was devised for use as a routine medium in the cultural 

 identification of members of the Salmonella and Shigella groups, showing hydro- 

 gen sulfide production, indole production and motility in the same tube. These 

 characteristics, along with other biochemical reactions, are of prime importance 

 in the cultural identification of members of the Gram-negative enteric group. 



Orlowski^ noted that Salmonella typhosa could be distinguished from the coli- 

 form organisms by culturing them in a medium containing lead acetate, an indi- 

 cator of hydrogen sulfide production. Jordan and Victorson- showed further that 

 S. paratyphi (paratyphoid A) and S. schottmuelleri (paratyphoid B) could be 

 distinguished on the basis of hydrogen sulfide production by growing them in a 

 Lead Acetate Medium. 



Semisolid media, as described by Hiss,^ Hesse,'* Jackson and Melia,^ Tittsler 

 and Sandholzer^ and others, have been employed quite extensively in the deter- 

 mination of motility by bacteria. Sulkin and Willett,^ in Bacto-Triple Sugar Iron 

 Agar, used 1 per cent agar to demonstrate motility or lack of motility in addition 

 to hydrogen sulfide production and carbohydrate fermentation by members of 

 the Salmonella and Shigella groups. They called attention to the "brush-like" 

 growth or motility of the typhoid organisms. Friewer and Shaughnessy^ used the 

 fermentation of lactose, hydrogen sulfide production and motility in a Lead 

 Acetate Semisolid Agar as a screening medium in the isolation of enteric patho- 

 gens from stool culture. Sosa^ described a peptone medium with a low agar con- 



