HiCrome™ Salmoconfirm Selective Agar

Intended Use

Recommended for the isolation, differentiation and confirmation of Salmonella species from coliforms from food, water and clinical samples by chromogenic method.

Composition**

Final pH (at 25°C): 7.0±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 42.75 gram in 1000 ml purified/distilled water. Heat to boiling to dissolve the medium completely. DO NOT AUTOCLAVE. Cool to 45-50°C. Mix well and pour into sterile Petri plates.

Principle And Interpretation

Salmonella species have been isolated from humans and almost all animals throughout the world. They cause many types of infections from mild, self-limiting gastroenteritis to life threatening typhoid fever. Salmonella Typhi and Salmonella Paratyphi A & B cause gastroenteritis, bacteremia and enteric fever, Salmonella Choleraesuis causes gastroenteritis and enteric fever, especially in children. Salmonella Typhimurium is the most frequently isolated serotype of Salmonella. Salmonella is a cause of food poisoning(1).

ISO 6539 specifies method for the detection, enumeration and serotyping of Salmonella from food and meat samples. After pre-enrichment and selective enrichment, the isolation is carried out on XLD Agar (M031I) and a second selective media has to be selected which is not based on H2S production (ISO).

XLD Agar is based on fermentation reaction and H2S production hence second medium should be selected so as to detect lactose positive and H2S negative strains. In addition to the positive control cultures (typical Salmonella), 3 additional Salmonella cultures are recommended to assist in the selection of atypical Salmonella colony morphology on selective agars. These cultures are a lactose-positive, H2S-positive Salmonella diarizonae (ATCC 12325) and a lactose-negative, H2S-negative Salmonella abortus equi (ATCC 9842); or a lactose-positive, H2S-negative Salmonella diarizonae (ATCC 29934).

This medium is based on chromogenic differentiation wherein Klebsiella and Enterobacter species gives blue colour coloured colonies. E.coli gives colourless to light mauve coloured colonies, Proteus gives light brown coloured colonies. All Salmonella species gives purple coloured colonies. Peptone special supplies nitrogeneous and carbonaceous compounds, long chain amino acids and other essential nutrients. Buffering agent buffers the medium. Chromogenic mixture imparts colour. Agar is the solidifying agent.

Type of specimen

Clinical samples- faeces, Food samples; Water samples

Specimen Collection and Handling

For clinical samples, follow appropriate techniques for sample collection and processing as per guidelines (1,2). For food samples, follow appropriate techniques for sample collection and processing as per guidelines (3,4). For water samples, follow appropriate techniques for sample collection, processing as per guidelines and local standards (5). After use, contaminated materials must be sterilized by autoclaving before discarding.

Warning and Precautions

In Vitro diagnostic use. 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. Individual organisms differ in their growth requirement and may show variable growth patterns on the medium.
2. Further biochemical and serological identification is necessary 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 Offwhite to pale yellow homogeneous free flowing powder

Gelling Firm, comparable with 1.5% Agar gel.

Colour and Clarity of prepared medium Off white coloured, opaque gel forms in Petri plates

Reaction Reaction of 4.3% w/v aqueous solution at 25°C. pH : 7.0±0.2

pH 6.80 -7.20

Cultural Response Cultural characteristics observed after an incubation at 35-37°C for 24-36 hours.

Key :*Corresponding WDCM numbers, # Formerly known as Enterobacter aerogenes, ## Formerly known as Proteus vulgaris

Storage and Shelf Life

Store dehydrated powder and prepared medium between 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 (1,2).

Reference

1. Isenberg, H.D. Clinical Microbiology Procedures Handbook. 2nd Edition.
2. 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.
3. Microbiology of the food chain- Horizontal method for the detection, enumeration and serotyping of Salmonella- Part I Detection of Salmonella . International Organization for Standardization (ISO), ISO/DIS 6579-1:2017.
4. Salfinger Y., and Tortorello M.L., 2015, Compendium of Methods for the Microbiological Examination of Foods, 5th Ed., American Public Health Association, Washington, D.C.
5. Lipps WC, Braun-Howland EB, Baxter TE,eds. Standard methods for the Examination of Water and Wastewater, 24th ed. Washington DC:APHA Press; 2023.