Salmonella

Description

Use and description:

For the selective differentiation of salmonella spp. from other pathogenic enterobacteriaceae from food and clinical specimens. Gram-positive bacteria are inhibited by bile salts, citrate. Salmonella spp. will grow as magenta colonies, Enterobacter spp. will grow as deep blue colonies.

 

Composition per liter:

Peptones………………………………………. 7.0 g

L-lysine  ………………………………………..0.5 g

L-cystine ……………………………………….0.1 g

Beef Extract ……………………………………5.0 g

Chromogenix mix……………………………0.30 g

Agar…………………………………………  …12.0 g

Yeast extract …………………………………..5.0 g

Xylose ………………………………………….1.75 g

 

Final pH of the ready to use medium:   7.0 ± 0.2

 

Medium preparation:

Add 31,7 grams of dehydrated culture medium to 1 liter of distilled water, and allow to soak for 10 minutes. Swirl to mix, then bring to the boil and autoclave at 121 C for 15 minutes. Dry the surface before incubation.

 

Quality specifications:

Dehydrated medium:  homogeneous, beige fine powder.

Ready to use medium:  straw coloured agar, clear to very slightly opalescent.

 

Microbiological response:

Organism	Result
Enterococcus faecalis ATCC 29212	Inhibited
Escherichia coli ATCC 25922	Partially inhibited, deep blue colonies
Salmonella typhimurium ATCC 14028	Growth, magenta colonies
Enterobacter aerogenes  ATCC 13048	Growth, deep blue colonies

 

Storage:

Dehydrated medium should be stored between 10 to 25^oC. Once opened, place the container in a dark, dry place. The dehydrated medium should not be used if there is any lump or if color has changed from the original.