Plot No. C40, Road No. 21Y, MIDC, Wagle Industrial Estate,
Thane(W)-400604, MH, India.
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Intended Use
Recommended for the selection, isolation and identification of Methicillin Resistant Staphylococcus aureus from clinical specimens.
Composition**
| Ingredients | Value |
|---|---|
| Tryptone | 10.000 g/L |
| HM peptone B # | 5.000 g/L |
| Glycine | 10.000 g/L |
| Sodium pyruvate | 10.000 g/L |
| Lithium chloride | 5.000 g/L |
| Mannitol | 10.000 g/L |
| Sodium chloride | 10.000 g/L |
| Indicator mixture | 0.130 g/L |
| Agar | 20.000 g/L |
| Methicillin (from MeRS Selective Supplement (FD229) - 2 vials) | 4.000mg |
| Cefoxitin (from CF Selective Supplement II (FD259) - 2 vials) | 6.000mg |
| Final pH (at 25°C) | 7.1±0.2 |
**Formula adjusted, standardized to suit performance parameters
# Equivalent to Beef extract
Directions
Either streak, inoculate or surface spread the test inoculum (50-100 CFU) aseptically on the plate.
Principle And Interpretation
Staphylococcus aureus sometimes referred to as "Staph" is a common bacterium found on the skin of healthy people. It is responsible for infections ranging from superficial to systemic (1,2). Staphylococcus aureus resistant to the antibiotic methicillin are referred to as Methicillin Resistant Staphylococcus aureus (MRSA) (3). Initially staphylococcal infections were treated using penicillin. But over the years, resistance to penicillin developed, so methicillin was the next drug of choice. Unfortunately certain strains (MRSA) have now developed resistance to methicillin also. Patients with breaks in their skin due to wounds, indwelling catheters or burns are those with certain risk of developing MRSA infection (4). Symptoms in serious cases may include fever, lethargy and headache. MRSA can cause UTI, pneumonia, toxic shock syndrome and even death. Spread of MRSA infections can be controlled to a great extent by maintaining personal hygiene after interaction with an MRSA infected person (3).
Methicillin-resistant strains of Staphylococcus aureus (MRSA) were recognized in 1980s as a major clinical and epidemiological problem. MRSA strains were heterogeneous in their expression of resistance to b-lactam agents, in that large differences in the degree of resistance were seen among the individual cells in a population. The basis of methicillin-resistance is the production of an additional penicillin-binding protein mediated by the mec A gene, an additional gene found in methicillin-resistant Staphylococci. MeReSa Agar Base was developed to detect the presence of the mec A gene in S. aureus i.e. methicillin-resistant S. aureus.
Tryptone and HM peptone B provide nitrogenous and carbonaceous compounds, long chain amino acids, vitamins and other essential nutrients. Lithium chloride and methicillin inhibit most of the contaminating microflora except methicillin-resistant S.aureus (MRSA). Glycine and sodium pyruvate enhance the growth of Staphylococcus species. Colour of the colonies is due to the indicator mixture and mannitol used in the medium. Sodium chloride maintains the osmotic equilibrium of the medium as well as supports the growth of Staphylococcus species.
Type of Specimen
Clinical samples: Tissue samples, wound swab, nasal swab.
Specimen Collection and Handling
For clinical samples follow appropriate techniques for handling specimens as per established guidelines (5,6). After use, contaminated materials must be sterilized by autoclaving before discarding.
Warning and Precautions
In Vitro diagnostic use only. 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 clinical specimens. Safety guidelines may be referred in individual safety data sheets.
Limitations :
- MRSA intermediate strains may show poor growth due to nutritional variations and resistance to methicillin / cefoxitin.
- Slight colour variation may be observed depending upon the utilization of the substrate by the organism.
- Other methicillin resistant Staphylococcus species may grow. Further biochemical tests must be carried out to differentiate between resistant strains.
- 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 tests must be carried out for further identification
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 MeReSa Agar in 90 mm disposable plates with smooth surface and absence of black particles/cracks/bubbles.
Colour: Pale pink coloured medium
Quantity of medium: 25 ml of medium in 90 mm disposable plate
pH: 6.90 -7.30
Sterility check: Passes release criteria
Cultural Response
Cultural characteristics observed after an incubation at 35-37°C for 18-48 hours.
| Organism | Inoculum (CFU) | Growth | Recovery | Colour of Colony |
|---|---|---|---|---|
| Escherichia coli ATCC 25922 (00013*) | >=10³ | inhibited | 0% | |
| Staphylococcus aureus subsp. aureus ATCC 25923 (00034*) | >=10³ | inhibited | 0% | |
| Staphylococcus aureus (MRSA) ATCC 43300 | 50-100 | good-luxuriant | >=50% | light pink |
| Staphylococcus epidermidis ATCC 12228 (00036*) | >=10³ | inhibited | 0% | |
| Staphylococcus gallinarum MTCC 2992 | >=10³ | inhibited | 0% | |
| Staphylococcus saprophyticus subsp. saprophyticus ATCC 15305 (00159*) | >=10³ | 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 clinical sample must be decontaminated and disposed of in accordance with current laboratory techniques (5,6).
| Product Name | MeReSa Agar Plate |
|---|---|
| SKU | MP1594 |
| Customized Product Available | No |
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