Description

Shigella Chromogenic Medium: Rapid Detection for Food and Clinical Samples

Shigella Chromogenic Medium is an innovative solution specifically designed for the rapid detection of Shigella in various samples, including food and patient stool specimens. This specialized medium allows microbiologists to quickly identify Shigella colonies, which appear white or colorless, while certain strains of Shigella sonnei exhibit a distinctive blue center. By utilizing this medium, laboratories can streamline their workflow and enhance the accuracy of pathogen detection.

Key Features and Benefits

When it comes to testing for foodborne pathogens, efficiency is crucial. The Shigella Chromogenic Medium supports rapid results through its unique formulation. Escherichia coli and coliforms are easily identifiable with green or yellow colonies, while Salmonella presents as yellow or colorless with a black center. Other contaminants show blue-green or yellow appearances, making differentiation straightforward. Notably, Proteus and Pseudomonas aeruginosa do not grow on this medium, ensuring a focused environment for Shigella detection.

Composition and Preparation

The medium comprises:

• Special Nutrients: 70.2 g/L
• Chromogenic Reagent: 0.4 g/L
• Agar: 15.0 g/L
• Final pH: 7.3 ± 0.1 at 25℃

To prepare the medium, simply suspend 17.12 g in 200 mL of distilled water, heat for one minute, and pour into sterile Petri dishes once cooled to 45-50℃. This straightforward preparation process ensures that laboratories can maintain a high throughput of sample testing.

Application Procedure

1. Sample Solution Preparation: Follow national standards such as SN or FDA guidelines.
2. Enrichment Culture: Transfer 25 g of the sample into 225 mL of GN Broth or Shigella Broth and incubate at 36 ± 1℃ for 18-24 hours.
3. Inoculation: Using a 3 mm inoculation loop, streak the enrichment broth onto the Shigella Chromogenic Medium, creating two plates.
4. Incubation: Cultivate at 36 ± 1℃ for 20-24 hours. After incubation, the typical Shigella colonies will be evident.
5. Serological and Biochemical Testing: Confirm findings with serological tests and a full set of biochemical assays.

Quality Control and Storage

Quality control measures ensure the reliability of results. The dehydrated powder exhibits good flowability and is grey-white to pale pink, while the prepared medium should be red solid. Store prepared plates in a dark place to avoid light exposure and ensure longevity (2-5 days). For the dehydrated powder, maintain storage temperatures between 2-8℃.

Conclusion

Utilizing Shigella Chromogenic Medium not only enhances the speed of Shigella detection but also provides a clear differentiation from other common pathogens. Laboratories seeking reliable, rapid testing solutions will find this medium invaluable. With its straightforward preparation and effective performance, Shigella Chromogenic Medium stands out as a top choice for food safety and clinical diagnostics, meeting the demands of modern microbiology.

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