Easter and Gibson Salmonella Medium

LAB 137

Description

A medium for the rapid detection of Salmonella spp conductance/impedance techniques. This medium is based on L 55 Selenite Cystine Broth and is supplemented with dulcitol T.M.A.O. (trimethylamine-N-oxide). Salmonella reduce T.M.A.O T.M.A. (trimethylamine) and, in so doing, increase the conducti of the medium which can be detected and measured by monito equipment such as Malthus.

Best results will be obtained by those customers using Pre-Enrichment Broth (LAB 136) and Salmonella Medium (LAB 137) bought from LAB M. These media are both manufactured with the same peptones, so that organisms ‘switched on' to utilising the substrates in LAB 136 can carry on metabolising the same substrates in LAB 137 significantly shortening the lag time.

Method for reconstitution

Weigh 2.5 grams of powder, disperse in 100ml of deionised water. Add 1 vial of X137 T.M.A.O./Selenite supplement. Swirl to mix, heat to boiling to effect sterilisation. When cool add 1ml of stock solution of L-cystine. Distribute into sterile conductance tubes or bottles. DO NOT AUTOCLAVE.

Stock solution of L-cystine

0.1gm L-cystine dissolved in 15ml of normal NaOH - add to 100ml sterile distilled water. Keep refrigerated. Discard after 1 month.

Appearance: Clear reddish/orange solution. A slight precipitate may form.

pH: 7.2 ± 0.2

Storage of Prepared Medium: capped container - up to 1 month at 15-20˚C in dark.

Inoculation: From LAB 136 Easter and Gibson Pre-Enrichment Broth.

Incubation: 37˚C aerobically connected to monitoring equipment.

Minimum Q.C. organisms: E. coli NCIMB 50034

1.18

Storage of Prepared Medium: Capped container - up to 1 month at 15-20˚C in dark.

References

Easter M. C. Gibson D. M. 1985. Rapid and automated detection of Salmonella by electrical measurements. J. Hyg. 94, 245-262.

Gibson D.M. 1987. Some modifications to the media for rapid automated detection of salmonellas by conductance. J.Appl. Bacteriol. 63, 299-304.

Ogden I.D., Cann P.C. 1987. A modified conductance medium for the detection of Salmonella spp. J. Appl. Bacteriol. 63, 359-464.