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Selenite Broth Base w/o Biselenite

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SKU:

M970

Recommended for the enrichment of Salmonallae species from food, dairy products and pathological specimens, on addition of selenite.

Description

Intended use

Selenite Broth Base w/o Biselenite is recommended for the enrichment of Salmonallae species from food, dairy products and pathological specimens, on addition of selenite.

Composition

Ingredients	g / L
Tryptone	5.000
Lactose	4.000
Sodium phosphate	10.000
Final pH (at 25°C)	7.0±0.2

Formula adjusted, standardized to suit performance parameters

Directions

Suspend 4.0 grams of sodium hydrogen selenite (M1079B) in 1000 ml purified/distilled water. Add 19.0 grams of medium (M970). Mix well. Warm to dissolve the medium completely. Distribute into sterile test tubes. Sterilize in a boiling water bath or free flowing steam for 10 minutes. DO NOT AUTOCLAVE. Excessive heating is detrimental. Discard the prepared medium if large amount of selenite is reduced (indicated by red precipitate at the bottom of tube/bottle).

Note: Instead of RM154, DD056 -Sodium Biselenite discs (1 disc per 10 ml of the medium) or DB001-Sodium Biselenite Bud (1 bud per 100ml of medium) can be added to the medium after boiling.

Principle And Interpretation

Klett (1) first demonstrated the selective inhibitory effects of selenite and Guth (2) used it to isolate Salmonella Typhi. Leifson fully investigated selenite and formulated the selenite media. Enrichment media are routinely employed for detection of pathogens in faecal specimens as the pathogens are present in a very small number in the intestinal flora. Selenite Broth is useful for detecting Salmonella in the non-acute stages of illness when organisms occur in the faeces in low numbers and for epidemiological studies to enhance the detection of low number of organisms from asymptomatic or convalescent patients (3).

Tryptone provides nitrogenous and carbonaceous compounds, long chain amino acids, and other essential nutrients. Lactose maintains the pH of medium. Selenite is reduced by bacterial growth and alkali is produced. An increase in pH lessens the toxicity of the selenite and results in overgrowth of other bacteria. The acid produced by bacteria due to lactose fermentation serves to maintain a neutral pH. Sodium phosphate maintains a stable pH and also lessens the toxicity of selenite. Enriched broth is subcultured on differential plating media such as Bismuth Sulphite Agar (M027), Brilliant Green Agar (M016), XLD Agar (M031) etc. Do not incubate the broth longer than 24 hours as inhibitory effect of selenite decreases after 6 - 12 hours of incubation (4).

Type of specimen

Clinical samples - faeces, urine; Food and dairy samples

Specimen Collection and Handling:

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

For food and dairy samples, follow appropriate techniques for sample collection and processing as per guidelines (7,8,9).

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 :

As this medium is highly selective it may not support the growth of all Salmonella species.
Recovery on selective medium is required for isolation.

Performance and Evaluation

Performance of the medium is expected when used as per the direction on the label expiry period when stored at within the recommended temperature.

Quality Control

Appearance
Cream to light yellow homogeneous free flowing powder

Colour and Clarity of prepared medium
Cream to yellow coloured clear solution without any precipitate

Reaction
Reaction of 1.9% w/v of medium along with 0.4% w/v selenite aqueous solution at 25°C. pH : 7.0±0.2

pH
6.80-7.20

Cultural Response
Cultural characteristics observed with added sodium hydrogen selenite (M1079B) when subcultured on MacConkey Agar (M081) after an incubation at 35-37°C for 18-24 hours.

Organism	Inoculum (CFU)	Recovery	Colour of colony
Escherichia coli ATCC 25922 (00013*)	50-100	none to poor	pink with bile (no increase in precipitate numbers)
Salmonella Choleraesuis ATCC 12011	50-100	good-luxuriant	colourless
Salmonella Typhi ATCC 6539	50-100	good-luxuriant	colourless
Salmonella Typhimurium ATCC 14028 (00031*)	50-100	good-luxuriant	colourless

Key: (*) corresponding WDCM numbers

Storage and Shelf Life

Store between 10-30°C in a tightly closed container and the prepared medium at 15-30°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

Klett A., 1900, Zeitsch Für Hyg. Und. Infekt., 33: 137.
Guth F., 1926, Zbl. Bakt. I. Orig., 77:487.
Kelly, Brenner and Farmer, 1985, Manual of Clinical Microbiology, 4th ed., Lennett and others (Eds.), ASM, Washington, D.C.
Chattopadhyay W. and Pilford J. N., 1976, Med. Lab. Sci., 33:191.
Isenberg, H.D. Clinical Microbiology Procedures Handbook. 2nd Edition.
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.

Product Information

More Information
Product Name	Selenite Broth Base w/o Biselenite
SKU	M970
Product Type	Regular
Physical Form	Powder
Origin	Animal
Packaging type	HDPE
References	1. Klett A., 1900, Zeitsch Für Hyg. Und. Infekt., 33: 137.2.Guth F., 1926, Zbl. Bakt. I. Orig., 77:487.3.Kelly, Brenner and Farmer, 1985, Manual of Clinical Microbiology, 4th ed., Lennett and others (Eds.), ASM, Washington,D.C.4.Chattopadhyay W. and Pilford J. N., 1976, Med. Lab. Sci., 33:191.5.Isenberg, H.D. Clinical Microbiology Procedures Handb0ook. 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.Lapage S., Shelton J. and Mitchell T., 1970, Methods in Microbiology', Norris J. and Ribbons D., (Eds.), Vol. 3A, AcademicPress, London.8.American Public Health Association, Standard Methods for the Examination of Dairy Products, 1978, 14th Ed., WashingtonD.C.9.Salfinger Y., and Tortorello M.L. Fifth (Ed.), 2015, Compendium of Methods for the Microbiological Examination ofFoods, 5th Ed., American Public Health Association, Washington, D.C.10.Wehr H. M. and Frank J. H., 2004, Standard Methods for the Microbiological Examination of Dairy Products, 17th Ed.,APHA Inc., Washington, D.C.
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