Plot No. C40, Road No. 21Y, MIDC, Wagle Industrial Estate,
Thane(W)-400604, MH, India.
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Intended use
Recommended for selective isolation and identification of Listeria species .
Composition
| Ingredients | g/L |
|---|---|
| HiVeg® peptone | 23.000 |
| Starch | 1.000 |
| Sodium chloride | 5.000 |
| Mannitol | 10.000 |
| Ammonium ferric citrate | 0.500 |
| Esculin | 0.800 |
| Dextrose (Glucose) | 0.500 |
| Lithium chloride | 15.000 |
| Phenol red | 0.080 |
| Agar | 13.000 |
| Final pH (at 25°C) | 7.0±0.2 |
**Formula adjusted, standardized to suit performance parameters
Directions
Suspend 69.0 grams in 1000 ml purified/distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool to 45-50°C and aseptically add rehydrated contents of 2 vials of Listeria Selective Supplement (PALCAM) (FD061). Mix well and pour into sterile Petri plates.
Principle And Interpretation
The genus Listeria constitutes Listeria monocytogenes, Listeria ivanovii, Listeria seeligeri, Listeria welshimerii, Listeria innocua, Listeria grayi, Listeria murrayi and Listeria denitrificans. Among these, L. monocytogenes and L. ivanovii are associated with diseases in humans. The pathogenicity of L.ivanovii is uncertain. L. monocytogenes is found in a wide variety of habitats, including the normal microflora of healthy ruminants, gastrointestinal tract of asymptomatic humans and environmental sources including river water, sewage, soil, silage, fertilizers and decaying vegetation (1). Listeria Identification Agar also known as Polymyxin-Acriflavin-Lithium chloride-Ceftazidime-Aesculin-Mannitol (PALCAM) Agar was formulated by Van Netten et al (2) and is recommended for the isolation of L. monocytogenes from foods. PALCAM medium is highly selective due to the presence of lithium chloride, ceftazidime, polymyxin B and acriflavin hydrochloride. PALCAM medium is a differential diagnostic medium utilizing two indicator systems, as esculin and ferric citrate and mannitol and phenol red. Listeria Identification HiVeg® Agar Base (PALCAM) is same as Listeria Identification Agar Base (PALCAM) except that the animal based peptones are completely replaced with vegetable peptones to avoid the BSE/TSE risks associated with animal peptones. HiVeg® peptone serves as carbon, nitrogen substances, long chain amino acids, vitamins and essential growth nutrients for the organisms. Dextrose (Glucose), starch and mannitol are the carbohydrate and energy sources. Sodium chloride maintains the osmotic equilibrium of the medium. Phenol red is the pH indicator dye that exhibits changes in the pH of the medium. L. monocytogenes hydrolyzes esculin to form esculetin and dextrose. Esculetin reacts with ammonium ferric citrate and forms a brown-black complex seen as a black halo around colonies. L.monocytogenes does not ferment mannitol but contaminants such as Enterococci and Staphylococci ferment mannitol and is indicated by colour change from red to yellow. Under microaerophilic conditions, strict aerobes such as Bacillus species and Pseudomonas species are inhibited. The addition of egg yolk (2.5% v/v) to PALCAM Agar has been reported to aid repair of damaged cells (3). Medium containing blood when overlaid on PALCAM Agar enables to differentiate and enumerate haemolytic Listeria species (4). Depending upon the type of sample used, selective enrichment broth should be used prior to inoculation onto PALCAM HiVeg® Agar. Generally Listeria Selective Enrichment Medium is used for dairy products and Listeria Selective Enrichment HiVeg® Medium Base UVM (MV890A), Fraser Secondary Enrichment HiVeg® Broth Base (MV1083) are used for meats and poultry. On PALCAM HiVeg® Agar, colonies of Listeria appear as grey-green with a black precipitate, following inoculation and incubation at 35°C for 24-48 hours under aerobic or microaerophilic conditions.
Type of specimen
Food samples; Water samples
Specimen Collection and Handling:
For food samples, follow appropriate techniques for sample collection and processing as per guidelines (5).
For water samples, follow appropriate techniques for sample collection, processing as per guidelines and local standards (6).
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 :
- The medium is not differential, so further biochemical testing is required for identification between Listeria species.
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
Light yellow to pink homogeneous free flowing powder
Gelling
Firm, comparable with 1.3% Agar gel.
Colour and Clarity of prepared medium
Red coloured clear to slightly opalescent gel forms in Petri plates.
Reaction
Reaction of 6.9% w/v aqueous solution at 25°C. pH: 7.0±0.2
pH
6.80-7.20
Cultural Response
MV1064: Cultural characteristics observed under microaerophilic condition, with added PALCAM Selective Supplement (FD061), after an incubation at 35-37°C for 24-48 hours.
| Organism | Inoculum (CFU) | Growth | Recovery | Colony characteristics |
|---|---|---|---|---|
| Enterococcus faecalis ATCC 29212 (00087*) | 50-100 | none-poor | <=10% | grey colonies with a brown-green halo |
| Listeria monocytogenes ATCC 19111 (00020*) | 50-100 | luxuriant | >=50% | grey-green with black center and a black halo |
| Listeria monocytogenes ATCC 19112 | 50-100 | luxuriant | >=50% | grey-green with black center and a black halo |
| Listeria monocytogenes ATCC 19117 | 50-100 | luxuriant | >=50% | grey-green with black center and a black halo |
| Listeria monocytogenes ATCC 19118 | 50-100 | luxuriant | >=50% | grey-green with black center and a black halo |
| Staphylococcus aureus subsp. aureus ATCC 25923 (00034*) | 50-100 | none-poor | <=10% | yellow colonies with yellow halo |
Key: (*) Corresponding WDCM numbers.
Storage and Shelf Life
Store between 10-30°C in a tightly closed container and the prepared medium at 2-8°C. Use before expiry date on the label. On opening, product should be properly stored dry, after tightly capping the bottle inorder to prevent lump formation due to the hygroscopic nature of the product. Improper storage of the product may lead to lump formation. Store in dry ventilated area protected from extremes of temperature and sources of ignition Seal the container tightly after use. 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 (7,8).
| Product Name | Listeria Identification HiVeg™ Agar Base (PALCAM) |
|---|---|
| SKU | MV1064 |
| Customized Product Available | No |
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PALCAM Selective Supplement
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