HiCrome™ Yersinia Agar Base

Intended Use

Recommended for detection and isolation of pathogenic Yersinia enterocolitica from clinical specimens and food samples.

Composition

Final pH (at 25°C): 7.4±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 57.93 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 reconstituted contents of 1 vial of CTN Selective Supplement (FD034). Mix well and pour into sterile petri plates.

Principle And Interpretation

Yersinia enterocolitica is widely distributed in lakes and reservoirs. Epizootic outbreaks of diarrhea, lymphadenopathy, pneumonia and spontaneous abortions occur in various animals. It is the most common species of Yersinia recovered from clinical specimens. Y. enterocolitica is biochemically more active at room temperature than at 37°C. Yersinia Selective Agar Base with added Yersinia Selective Supplement is used to isolate Y. enterocolitica from clinical and food samples (1). Yersinia Selective Agar Base is recommended for selective isolation of Yersinia (2,3) with modification of chromogenic identification.

Peptone mix and growth factor provides nitrogen and carbon source, long chain amino acids, vitamins and other essential growth nutrients. The medium is selective due to the presence of selective mix, which inhibit gram-positive and a number of gram-negative bacteria. Addition of antibiotic supplement makes it highly selective for Yersinia, thus imparting additional selectivity. One of the chromogen is split by Yersinia species and results in purple coloured colonies. Other organisms are either inhibited or results in colourless colonies. For the isolation of Y. enterocolitica by direct plating and pour plating, inoculate the specimen directly onto the medium. Incubate at 22-32°C for 24-48 hours or suspend the sample (food, faeces, etc.) in sterile Phosphate Buffer Saline and incubate for upto 21 days (4) at 4°C.

Type of specimen

Clinical samples - feaces, urine, throat swabs, etc.; Food samples

Specimen Collection and Handling

For clinical samples follow appropriate techniques for handling specimens as per established guidelines (5,6).

For food samples, follow appropriate techniques for sample collection and processing as per guidelines (7).

After use, contaminated materials must be sterilized by autoclaving before discarding.

Warning and Precautions

In Vitro diagnostic Use only. For professional 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

1. Due to variable nutritional requirements, some strains show poor growth on this medium.
2. Since it is an enzyme based reaction, slight colour variation may be observed depending upon strains.
3. Final confirmation of suspected colonies must be carried out by serological and biochemical tests.

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 greenish yellow homogeneous free flowing powder.

Gelling: Firm, comparable with 1.25% Agar gel.

Colour and Clarity of prepared medium: Reddish purple coloured clear to slightly opalescent gel forms in Petri plates.

Reaction: Reaction of 5.8% w/v aqueous solution at 25°C. pH : 7.4±0.2

pH: 7.20-7.60

Cultural Response: Cultural characteristics observed with added CTN Selective Supplement (FD034) after an incubation at 22-32°C for 24-48 hours.

Key : (*) Corresponding WDCM numbers.

Storage and Shelf Life

Store between 15-25°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 in order 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 clinical sample must be decontaminated and disposed of in accordance with current laboratory techniques (5,6).

Reference

1. International Organization for Standardization (ISO), 1994, Draft ISO/DIS 10273.
2. Schiemann D. A., 1979, Can. J. Microbiol., 25: 1298.
3. Schiemann D. A., 1980, Can. J. Microbiol., 26: 1232.
4. Weissfeild and Sonnenwirth, 1982, J. Clin. Microbiol. 15 :508.
5. Isenberg, H.D. Clinical Microbiology Procedures Handbook. 2nd Edition.
6. 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.
7. 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.