Plot No. C40, Road No. 21Y, MIDC, Wagle Industrial Estate,
Thane(W)-400604, MH, India.
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Intended Use
Recommended for detection of deoxyribonuclease activity of bacteria and fungi and especially for identification of pathogenic Staphylococci.
Composition**
| Ingredients | Gms / Litre |
|---|---|
| Tryptose | 20.000 |
| Deoxyribonucleic acid (DNA) | 2.000 |
| Sodium chloride | 5.000 |
| Methyl green | 0.050 |
| Agar | 15.000 |
| Final pH (at 25°C) | 7.3±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
DNase test Agar is used for detecting deoxyribonuclease activity of bacteria and fungi and particularly for identification of pathogenic Staphylococci (1). DNase producing organisms exhibit clear zone around growth against green background. Reagent addition is not required (2). This medium is based on modification of the procedure for detecting DNase-producing bacteria as per Smith, Hanoch, and Rhoden (3) and Jefferies, Holtman and Guse (4). The medium supports growth of both gram positive and gram-negative bacteria.
Tryptose serves as nitrogenous source for the organisms. DNase produced by microorganisms depolymerizes the DNA substrate in the medium. Methyl green fades into a colourless compound producing distinct clear zones surrounding colonies (or band/spot inocula) in an otherwise green coloured medium. Methyl green requires a highly polymerized DNA substrate (5) and it combines with polymerized DNA forming a stable, green complex at pH 7.5 (6-8). As hydrolysis progresses, methyl green is released and when not combined at this pH it fades and becomes a colourless compound. Therefore clear zones are observed (7,9).
Type of specimen
Isolated Microorganism from non clinical samples
Specimen Collection and Handling:
For isolated microorganism samples, follow appropriate techniques for sample collection and processing as per guidelines (1,3). 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 sheet
Limitations :
- The test organisms must be in pure culture and 18-24 hours old.
- 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 need to be carried out 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 DNase Test Agar Plate w/ Methyl Green in 90 mm disposable plates with smooth surface and absence of black particles/cracks/bubbles
Colour of medium
Greenish blue coloured medium
pH
7.10-7.50
Sterility Check
Passes release criteria
Cultural Response
Cultural characteristics observed after an incubation at 35-37°C for 18-24 hours
| Organism | Inoculum (CFU) | Growth | DNase Activity |
|---|---|---|---|
| Serratia marcescens ATCC 8100 | 50-100 | luxuriant | positive, clear halo around the growth. |
| Staphylococcus aureus subsp. aureus ATCC 25923 (00034*) | 50-100 | luxuriant | positive, clear halo around the growth. |
| Staphylococcus epidermidis ATCC 12228 (00036*) | 50-100 | luxuriant | negative reaction |
| Streptococcus pyogenes ATCC 19615 | 50-100 | luxuriant | positive, clear halo around the growth. |
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 (10,11).
| Product Name | DNase Test Agar Plate w/ Methyl green |
|---|---|
| SKU | MP1419 |
| Customized Product Available | No |
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