Penicillin and Pimaricin Pseudomonas Agar Base (PP Pseudomonas Agar Base)

Intended Use

Recommended for selective isolation of Pseudomonas species on addition of supplements. The composition and performance criteria are in accordance with ISO /TS 11059 .

Composition**

Penicillin and Pimaricin Pseudomonas Agar Base

Final pH ( at 25°C) 7.2±0.2

Supplements to be added

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 52.4 gram 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 sterile rehydrated contents of PP Selective Supplement (FD264) and PP Selective Supplement II (FD265). Mix well and pour into sterile Petri plates.

Principle And Interpretation

Pseudomonas species are aerobic, non-spore forming, gram negative rods, found in water, soil and plants including fruits and vegetables. Pseudomonas aeruginosa has become increasingly recognized as an emerging opportunistic pathogen of clinical relevance especially in patients with compromised host defense mechanisms. Several different epidemiological studies have found its occurrence as a nosocomial pathogen (6). Ps.aeruginosa strains produces two types of soluble pigments, the fluorescent pigment pyoverdin and the blue pigment pyocyanin. Pyocyanin (from "pyocyaneus") refers to "blue pus", which is a characteristic of suppurative infections caused by Ps.aeruginosa. Penicillin and Pimaricin Pseudomonas Agar Base is formulated as recommended by ISO Committee (3).

The medium contains gelatin peptone and tryptone which serves provides essential nitrogenous nutrients and carbon, long chain amino acids and vitamins required for the growth of Pseudomonas. Potassium sulphate and magnesium chloride serves to enhance pigment production. Addition of PP Selective Supplement which contains Penicillin and PP Selective Supplement II which contains Pimaricin (natamycin) to the medium helps in the selective isolation of Pseudomonas, thereby inhibiting the accompanying flora.

Type of specimen

Food and dairy samples

Specimen Collection and Handling

For food and dairy 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

1. Individual organisms differ in their growth requirement and may show variable growth patterns on the medium.
2. 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.

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 Cream to yellow homogeneous free flowing powder

Gelling Firm,comparable with 1.5% Agar gel

Colour and Clarity of prepared medium Yellow coloured clear to slightly opalescent gel forms in Petri plates

Reaction Reaction of 5.24% w/v aqueous solution at 25°C. pH : 7.2±0.2

pH 7.00-7.40

Cultural Response Productivity : Cultural characteristics observed with added PP Selective Supplement (FD264) and PP Selective Supplement II (FD265), after an incubation at 25° ± 1°C for 48 ± 2 hours. Recovery is considered as 100% on Soyabean Casein Digest Agar Selectivity: Cultural characteristics observed with PP Selective Supplement (FD264) and PP Selective Supplement II (FD265), after an incubation at 25° ± 1°C for 48 ± 2 hours.

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 (4,5).

References

1. Salfinger Y., and Tortorello M.L. Fifth (Ed.), 2015, Compendium of Methods for the Microbiological Examination of Foods, 5th Ed., American Public Health Association, Washington, D.C.
2. Milk and milk products - Method for the enumeration of Pseudomonas spp. International Organization for Standardization, 2009, Draft ISO/TS 11059:2009 (E).
3. Microbiology of food,animal feeding stuffs and water- Preparation, production,storage and performance testing of culture media, EN ISO 11133:2014 (E) /Amd. :2020 .
4. Isenberg, H.D. Clinical Microbiology Procedures Handbook 2nd Edition.
5. Jorgensen, J.H., Pfaller, M.A., Carroll, K.C., Funke, G., Landry, M.L., Richter, S.S and Warnock., D.W. (2015) Manual of Clinical Microbiology, 11th Edition. Vol. 1.