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Material Safety Data Sheet

Required Products

Organisms

Organisms this product works with:

Dehydrated Culture Media

MANNITOL SELENITE BROTH BASE
(See Selenite Broth Base)

Code: CM0399

A modification of Selenite F Broth especially recommended for the enrichment of salmonellae.

Typical Formula*

gm/litre

Bacteriological peptone

5.0

Mannitol

4.0

Sodium phosphate

10.0

pH 7.1 ± 0.2 @ 25°C

 
* Adjusted as required to meet performance standards

Directions
Add 19g to 1 litre of distilled water to which 4g of sodium biselenite LP0121 has been added.
Warm to dissolve, mix well and fill out into containers. Sterilise in a boiling water bath, or in free flowing steam, for 10 minutes.
DO NOT AUTOCLAVE.

To minimise any possible risk of teratogenicity to laboratory workers, the sodium biselenite must be added to this medium separately1.

Description
This medium is similar to the modification of Leifson2 enrichment medium described by Hobbs & Allison3 for the isolation of Salmonella typhi and Salmonella paratyphi B. Liefson2 suggested that it is best to tube the medium to a depth of 2 inches (50mm) or more.

Hobbs & Allison3 compared two sets of selenite media, one containing lactose and the other mannitol. Of 38 positive stools Salmonella typhi. was sub-cultured from both media in 32 instances, from the mannitol selenite alone in 5 instances and from the lactose selenite alone once. Comparisons showed that the mannitol selenite broth was superior to three other liquid media in its selective value for Salmonella typhi and that it was as good as tetrathionate for the isolation of Salmonella paratyphi B.

Technique
Sub-cultures from this selective, enrichment broth can be made to any combination of greater and lesser inhibitory selective agars for the Enterobacteriaceae.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8°C away from light.

Appearance
Dehydrated medium: Straw coloured, free-flowing powder
Prepared medium: Light straw coloured solution

Quality control

Positive control:

Expected results

Salmonella Typhimurium ATCC® 14028*

Good growth

Negative control:

 

Escherichia coli ATCC® 25922 *
Sub-culture to MacConkey Agar

Inhibited or no growth

* This organism is available as a Culti-Loop®

Precautions
Observe the precautionary comments made about sodium biselenite in Selenite Broth Base CM0395.
Discard the prepared medium if large amounts of reduced selenite can be seen as a red precipitate in the bottom of the bottle.
Do not incubate longer than 24 hours because the inhibitory effect of selenite is reduced after 6-12 hours incubation.
Mannitol fermentation by salmonella helps correct the alkaline pH swing which can occur during incubation.
Take sub-cultures of broth from the upper third of the broth column, which should be at least 5 cm in depth.

References
1. Robertson D.S.F. Lancet i 518-519.
2.
Leifson E. (1936) Am. J. Hyg. 24(2). 423-432.
3. Hobbs Betty C. and Allison V. D. (1945) Mon. Bull. Min. Hlth Pub. Hlth Lab. Serv. 4. 12-19.

 
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