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Technical Data
Selenite Cystine Broth Base M1079
Intended Use:
Recommended as a selective enrichment media for Salmonella and possibly Shigella sonnei from faeces, urine, water and
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foodstuffs.
Composition**
Ingredients Gms / Litre
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Tryptone 5.000
Lactose 4.000
Disodium hydrogen phosphate 10.000
L-Cystine 0.010
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Final pH ( at 25°C) 7.0±0.2
**Formula adjusted, standardized to suit performance parameters
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Directions
Suspend 19.01 grams in 1000 ml purified / distilled water. Add 4 grams of sodium hydrogen selenite (M1079B). Warm to
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dissolve the medium completely. Distribute in 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
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selenite is reduced (indicated by red precipitate at the bottom of tube/bottle).
Note : Instead of M1079B , 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
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Klett (1) first demonstrated the selective inhibitory effects of selenite and Guth (2) used it to isolate Salmonella Typhi.
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Leifson fully investigated selenite and formulated the media. Selenite Cystine Medium is a modification of Leifsons (3)
formula with added cystine (4). Modification of original composition and similar media are recommended by AOAC,
APHA, USP etc (3-7,8,9). 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 Cystine Broth is useful for detecting Salmonella
in the nonacute stages of illness when organisms occur in the faeces in low numbers and for epidemiological studies to
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enhance the detection of low number of organisms from asymptomatic or convalescent patients (10).
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Tryptone provides nitrogenous and carbonaceous compounds, long chain amino acids, vitamins 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. L-cystine improves recovery of Salmonella.
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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
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6 - 12 hours of incubation (11).
Type of specimen
Clinical : faeces, urine, water samples and foods.
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Specimen Collection and Handling
For clinical samples follow appropriate techniques for handling specimens as per established guidelines (12,13).
For food and dairy samples, follow appropriate techniques for sample collection and processing as per guidelines (5,7).
For water samples, follow appropriate techniques for sample collection, processing as per guidelines and local standards (9).
After use, contaminated materials must be sterilized by autoclaving before discarding.
Please refer disclaimer Overleaf.
HiMedia Laboratories Technical Data
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. Overheating of the medium leads to loss of selectivity of the medium.
2. Further isolation and biochemical tests must be carried out for confirmation.
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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.
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Quality Control
Appearance
Cream to light yellow homogeneous free flowing powder.
Colour and Clarity of prepared medium
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Cream to yellow coloured clear solution without any precipitate.
Reaction
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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
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6.80-7.20
Cultural Response
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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 Recovery Colour of
(CFU) colony
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Escherichia coli ATCC 50-100 none to poor pink with bile
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25922 (00013*) (no increase in precipitate
numbers)
Salmonella Choleraesuis 50-100 good-luxuriant colourless
ATCC 12011
Salmonella Typhi 50-100 good-luxuriant colourless
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ATCC 6539
Salmonella Typhimurium 50-100 good-luxuriant colourless
ATCC 14028 (00031*)
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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 in order to prevent
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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.
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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
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contact with clinical sample must be decontaminated and disposed of in accordance with current laboratory techniques
(12,13).
Reference
1. Klett A., 1900, Zeitsch Für Hyg. Und. Infekt., 33: 137.
2. Guth F., 1926, Zbl. Bakt. I. Orig., 77:487.
3. Leifson E., 1936, Am. J. Hyg., 24(2) : 423.
Please refer disclaimer Overleaf.
HiMedia Laboratories Technical Data
4. North W.R. and Bartran M.T., 1953, Appl. Microbiol., 1:130.
5. 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.
6. United States Pharmacopoeia, 2002, USP 25/NF 20, Asian Edition, United States Pharmacopeial Convention, Inc.,
Rockville, MD.
7. Wehr H. M. and Frank J. H., 2004, Standard Methods for the Microbiological Examination of Dairy Products, 17th
Ed., APHA Inc., Washington, D.C.
8. AOAC, 1978, Bacteriological Analytic Manual, 5th ed., AOAC, Washington, DC
9. Lipps WC, Braun-Howland EB, Baxter TE,eds. Standard methods for the Examination of Water and Wastewater,
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24th ed. Washington DC:APHA Press; 2023.
10. Kelly, Brenner and Farmer, 1985, Manual of Clinical Microbiology, 4th ed., Lennett and others (Eds.), ASM,
Washington, D.C.
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11. Chattopadhyay W. and Pilford J. N., 1976, Med.Lab. Sci., 33:191.
12. Isenberg, H.D. Clinical Microbiology Procedures Handbook. 2nd Edition.
13. 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.
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Revision : 03/2023
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Plot No.C-40, Road No.21Y, medical device
MIDC, Wagle Industrial Area,
Thane (W) -400604, MS, India 10°C
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Disclaimer :
User must ensure suitability of the product(s) in their application prior to use. Products conform solely to the information contained in this and
other related HiMedia™ publications. The information contained in this publication is based on our research and development work and is to the best
of our knowledge true and accurate. HiMedia™ Laboratories Pvt Ltd reserves the right to make changes to specifications and information related
to the products at any time. Products are not intended for human or animal or therapeutic use but for laboratory,diagnostic, research or further
manufacturing use only, unless otherwise specified. Statements contained herein should not be considered as a warranty of any kind, expressed or
implied, and no liability is accepted for infringement of any patents.
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