Plot No. C40, Road No. 21Y, MIDC, Wagle Industrial Estate,
Thane(W)-400604, MH, India.
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Intended Use
Recommended for the detection and enumeration of Escherichia coli in foods without further confirmation on membrane filter or by indole reagent. The composition and performance of this media are as per specifications laid down in in ISO 16649-2:1999.
Composition**
| Ingredients | Gms / Litre |
|---|---|
| Tryptone | 20.000 |
| Bile salts mixture | 1.500 |
| X-Glucuronide | 0.075 |
| Agar | 15.000 |
| Final pH (at 25°C) | 7.2±0.2 |
**Formula adjusted, standardized to suit performance parameters
Directions
Either streak, inoculate or surface spread the test inoculum (50-100 CFU) aseptically on the plate.
Principle And Interpretation
HiCrome™ E.coli Agar is based on Tryptone Bile Agar to detect Escherichia coli in foods (1), where recovery of E.coli is faster, more reliable and accurate. Most of the E.coli strains can be differentiated from other coliforms by the presence of enzyme glucuronidase, which is highly specific for E.coli (2). The chromogenic agent X-glucuronide used in this medium helps to detect glucuronidase activity of E.coli. E.coli cells absorb X-glucuronide and the intracellular glucuronidase enzyme splits the bond between the chromophore and the glucuronide. The released chromophore gives bluish green colouration to the E.coli colonies. The formulation is in accordance with ISO 16649-2 (3). It can also be used to isolate E.coli from samples.
Tryptone provides carbon, nitrogen compounds, long chain amino acids, vitamins and other essential growth nutrients to the organisms. Bile salts mixture inhibits gram-positive organisms. The surface of the plated medium is dried before use. Dilute food samples 1:5 or 1:10 with 0.1% (w/v) sterile Peptone Water (M028) and homogenize in a blender or a stomacher. Pipette 0.5 ml or 1.0 ml of the homogenized food sample on to the plate and spread with sterile glass spreader. Incubate the plates at 30°C for 4 hours and then at 44°C for 18 hours.
Type of specimen
Food samples
Specimen Collection and Handling
For food samples, follow appropriate techniques for sample collection and processing as per guidelines (3). After use, contaminated materials must be sterilized by autoclaving before discarding.
Warning and Precautions
Read the label before opening the container. Wear protective gloves/protective clothing/eye protection/face protection. Follow good microbiological lab practices while handling specimens and culture. Standard precautions as per established guidelines should be followed while handling specimens. Safety guidelines may be referred in individual safety data sheets.
Limitations
- B-glucuronidase is present in 97% of E.coli strains, however few E.coli may be negative.
- Certain species of Salmonella are β-glucuronidase positive.
- Individual organisms differ in their growth requirement and may show variable growth patterns on the medium.
- Each lot of the medium has been tested for the organisms specified on the COA. It is recommended to users to validate the medium for any specific microorganism other than mentioned in the COA based on the user's unique requirement.
- Further biochemical and serological test are necessary for confirmation.
Performance and Evaluation
Performance of the medium is expected when used as per the direction on the label within the expiry period when stored at recommended temperature.
Quality Control
Appearance
Sterile HiCrome™ E. coli Agar Plate in 90 mm disposable plates with smooth surface and absence of black particles/cracks/bubbles
Colour of medium
Light yellow coloured medium
Quantity of medium
25 ml of medium in 90 mm disposable plates.
pH
7.00-7.40
Sterility Check
Passes release criteria
Cultural Response
Cultural characteristics observed after an incubation at 44°C (35-37 in coa) for 18-24 hours.
| Organism | Inoculum (CFU) | Growth | Recovery | Colour of Colony |
|---|---|---|---|---|
| Escherichia coli ATCC 25922 (00013*) | 50-100 | luxuriant | >=50% | bluish green |
| Salmonella Enteritidis ATCC 13076 (00030*) | 50-100 | luxuriant | >=50% | colourless |
| Staphylococcus aureus subsp. aureus ATCC 25923 (00034*) | >=104 | inhibited | 0% |
Key: *Corresponding WDCM numbers.
Storage and Shelf Life
On receipt store between 2-8°C. Use before expiry date on the label. Product performance is best if used within stated expiry period.
Disposal
User must ensure safe disposal by autoclaving and/or incineration of used or unusable preparations of this product. Follow established laboratory procedures in disposing of infectious materials and material that comes into contact with sample must be decontaminated and disposed of in accordance with current laboratory techniques (5,6).
| Product Name | HiCrome™ E. coli Agar Plate |
|---|---|
| SKU | MP1295I |
| Customized Product Available | No |
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