Irgasan Ticarcillin and Potassium Chlorate Broth (ITC) ISO

Enzymatic casein digest provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group, essential for bacterial growth. Magnesium chloride and malachite green make the broth highly selective. Irgasan inhibits Gram-positive bacteria, ticarcillin has a bactericidal action on Gram-negative and Gram-positive bacteria and potassium chlorate has a disinfecting property.

Preparation

Suspend 44.0 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Sterilize in autoclave at 121 °C for 15 minutes. Cool to 47 °C and aseptically add two vials of ITC Supplement (LC-6051). Homogenize gently and dispense into sterile containers.

According to ISO 10273

Detection of Yersinia enterocolitica according to ISO 10273:

1. Obtain the initial suspension. Add a test portion of 25 g or 25 mL to 225 g or 225 mL of Sorbitol Peptone Broth and Bile Salt (PSB) (LC-1298) to obtain a tenfold dilution, and homogenize.
2. Inoculate the suspension (direct plating) onto 2 to 4 selective agar plates of Yersinia Selective Agar (CIN) (LC-1126).
3. Transfer the initial suspension in the liquid enrichment medium PSB to the selective enrichment medium Irgasan Ticarcillin and Potassium Chlorate Broth (ITC), and incubate the two enrichment liquid media at a temperature of 25 °C for 44 hours.
4. Plate out the enrichment with KOH treatment (mixing 0.5 mL of enrichment in 4.5 mL of 0.5% KOH solution for 20 s) on plates of Yersinia Selective Agar (CIN).
5. Incubate the plates of Yersinia Selective Agar (CIN) at 30 °C for 24 hours.
6. Verify the colony morphology as presumptive pathogenic Y. enterocolitica by successive culturing on selective plates. Typical colonies of Y. enterocolitica will appear colorless, with dark red centers, like bull's eye, surrounded by a transparent border.
7. Confirm the presence of pathogenic Y. enterocolitica species by biochemical or molecular confirmation test.

• ISO 10273 Microbiology of food and animal feeding stuffs - Horizontal method for the detection of presumptive pathogenic Yersinia enterocolitica.