Chromogenic Dehydrated Culture Media
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 25oC. 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.