Shigella Chromogenic Agar is a selective chromogenic medium specifically designed for rapid detection of Shigella species. It is widely used in food safety, clinical stool sample analysis, and public health surveillance. Its formulation relies on specific enzyme-substrate reactions. By mixing chromogenic agents, it causes Shigella species (including Shigella flexneri, Shigella dysenteriae, Shigella boydii, and Shigella sonnei) to form white to colorless colonies, with Shigella sonnei often exhibiting a characteristic blue center. Escherichia coli and coliform bacteria appear green or yellow, while Salmonella species exhibit yellow or colorless colonies with black centers (due to hydrogen sulfide production). Growth of contaminants such as Proteus spp. and Pseudomonas aeruginosa is significantly inhibited.

Initial screening of Shigella in diarrhea feces: Shigella was isolated from bacterial dysentery and infectious diarrhea feces, and color differentiation was used to distinguish miscellaneous bacteria and shorten the interpretation time.

Identification and isolation of intestinal pathogenic bacteria: distinguish Shigella (white/colorless), Escherichia coli (green), Salmonella (black heart), inhibit the migration of Proteobacteria, and reduce false negatives.

Traceability testing of food poisoning: Simultaneous screening of collective food poisoning vomit and suspicious food ingredients to quickly identify the source of Shigella infection.

Routine screening of intestinal clinics: Batch fecal high-throughput separation, suitable for large-scale screening during outbreaks of dysentery and summer epidemics of intestinal infectious diseases.

Identification between EIEC and Shigella: Pure white suspicious colonies are combined with biochemistry and serum to distinguish invasive Escherichia coli from Shigella and avoid misdiagnosis.

Shigella genus

Biological characteristics: Gram negative Bacillus subtilis, lacking flagella, motility, and spores; Facultative anaerobic; Not fermenting lactose, not producing H ₂ S; invasive pathogenic bacteria, causing bacterial dysentery; It is divided into four groups: dysentery, Fukushi, Bao, and Shigella. Shigella can slowly ferment lactose.

Characteristics of bacterial colonies in chromogenic culture medium: Shigella flexneri/Shigella flexneri: white/colorless, smooth semi transparent, round convex, with a diameter of 1-3mm, with a reddish purple color on the culture substrate and no black center; Song Nei Shiga: White colonies with a center that often appears light blue; After cultivation for more than 24 hours, slight powdering can occur.