【 Principle 】

Peptone provides the carbon source, nitrogen source, and growth factors required for bacterial growth; Bile salt No. 3, crystal violet, and cefuroxime mainly inhibit the growth of Gram positive bacteria; Potassium tellurite inhibits the growth of non Escherichia coli O157: H7 Gram negative bacteria; Bacteria using D-sorbitol grow and produce acid on this medium, causing the acid-base indicator in the medium to turn neutral red and make the bacterial cells red. Escherichia coli O157: H7 does not ferment D-sorbitol, and the growing colonies on this medium appear colorless.

Main components

Composed of peptone, sorbitol, bile salt 3, neutral red, crystal violet, sodium chloride, agar, potassium tellurite, cefuroxime, 95% ethanol, and distilled water.

Storage conditions and expiration date

Storage conditions: This product should be stored in a dark environment at 2-8 ℃.

Validity period: The unopened original packaging has a validity period of 6 months.

This product is a disposable product.

Food O157: H7 preliminary screening: After adding bacteria to fresh meat, fruits and vegetables, draw lines and specifically isolate hemorrhagic Escherichia coli O157: H7.

Food poisoning screening: Vaccination of feces and vomit from patients with hemorrhagic diarrhea to quickly screen for suspected O157: H7 and assist in etiological diagnosis.

Monitoring of processing environment: detecting samples applied to slaughterhouses, cutting tools, and cold chain containers, tracing pollution sources, and blocking cross contamination.

Detection of pathogenic bacteria in water sources: Screening for O157: H7 in surface water and processing wastewater to assess drinking water safety risks.

Purification of positive samples: Modify the EC broth turbidity tube and transfer to CT-SMAC to obtain colorless suspicious colonies for subsequent identification.

Import and export quarantine: sampling fresh and processed meat products to quickly distinguish between O157: H7 and common coliforms.

Disinfection effect verification: After disinfection, the sample was coated with bacteria and residual O157: H7 was detected to evaluate the killing effect.

Culture medium control: O157: H7 is a colorless colony (positive), while ordinary Escherichia coli is a red colony (negative)

Escherichia coli O157: H7

Biological characteristics: G-short rod-shaped bacteria, flagella, facultative anaerobic, no spores; Non fermented sorbitol (different from ordinary Escherichia coli); Tolerant to bile salts; Shiga like toxin production; Heat resistant (able to proliferate at 44.5 ℃), low temperature resistant (for fresh produce and long-term survival in water bodies);

 EHEC hemorrhagic Escherichia coli can cause bloody diarrhea and lead to hemolytic uremic syndrome.

Colony characteristics: Color development principle - 

sorbitol replaces lactose, fermentation produces acid producing colonies that turn red (indicated by neutral red); O157: H7 typical colony, color, semi transparent, smooth round, with clear edges; Compared to ordinary Escherichia coli, ordinary bacteria ferment sorbitol → red/pink colonies, visually distinguishing; Cefoxime inhibits G-bacteria, while potassium tellurite inhibits G+bacteria and reduces background interference.