Shigella Chromogenic Medium is specially used for the rapid detection of Shigella in food and patient stool samples. The colonies of Shigella are white or colorless, some sonnei Shigella have blue center; Escherichia coli and Coliforms have green or yellow colonies; salmonella are yellow or colorless and have a black center; other are blue-green or yellow. Proteus and Pseudomonas aeruginosa basically do not grow; it is an ideal culture medium for rapid detection.

Ingredients (g/L):

*Adjusted and/or supplemented as required to meet performance criteria

Directions:

Suspend 17.12g of the medium in 200mL of distilled water, heat in 1 minute. When cooling to 45-50 ℃, pour into sterile petri dishes.

Warning: 

Prepared medium must be kept dry, can place inverted culture in incubator at 36 ± 1 ℃ for 1-2 hours.

Procedures:

1. Prepared sample solution according to national standards, SN standard, FDA standards or other methods.

2. Transfer 25g sample solution into 225mL GN Broth or Shigiella Broth, enrichment culture for 18- 24hours at 36 ± 1 ℃;

3. Take one ring enrichment broth with a 3mm inoculation loop, streak to inoculated o Shigella Chromogenic Medium, make two plates

4. Culture at 36 ± 1 ℃ for 20-24 hours, the colonies of Shigella are white or colorless, some sonnei Shigella have blue center; Escherichia coli and Coliforms have green or yellow colonies; salmonella are yellow or colorless and have a black center; other are blue-green or yellow. Proteus and Pseudomonas aeruginosa basically do not grow

5.  For typical colonies, do Shigella serological test and full set of biochemical tests.

Quality Control:

1. Appearance:

The dehydrate powder medium is homogeneous, having good flowability, grey white to pale pink, prepared medium is red solid.

2. Microbial sensitivity test:

Incubated at 36 ± 1 ℃ 18-24h:

Methods limitations:

The typical Shigella on t medium must be do serological test and biochemical tests

Typical features:

The colonies of Shigella are white or colorless, some sonnei Shigella have blue center; Escherichia coli and Coliforms have green or yellow colonies; salmonella are yellow or colorless and have a black center; other are blue-green or yellow. Proteus and Pseudomonas aeruginosa basically do not grow.

Storage:

The prepared plates can be kept for 2-5 days, avoid direct exposure to light. The powder medium should be placed in a dark, dry place, storage temperature 2-8 ℃, avoid direct exposure to light.

Failure:

Dry powder media which are over the shelf life, caking and color variation cannot be used.

Note:

This medium is only for laboratory use.

Reference:

1. Restaino, L., E. W. Frampton, W. C. Lionberg, and A. L. Restaino. 2007. Detection of Shigella sp.using a selective and differential chromogenic plating medium. Abstract P3-43. IAFP.