MSRV Medium Base, modified

MSRV Medium Base Modified

EMD Cat. No. 1.09878.0500

500 g

MSRV Medium is a semi-solid medium used for the isolation of Salmonella from food-stuffs and other materials.

Additives

EMD Cat. No.	Product	Pack Size
1.07228.0500	Buffered Peptone Water	500 g
1.07228.5000	Buffered Peptone Water	5 kg
1.09874.0001	MSRV Selective-Supplement	1 x 16 vials

Mode of Action	Preparation
Experimental Procedure and Evaluation	Quality Control
Typical Composition (g/liter)	Literature
Picture/Image

Mode of Action
De SMEDT et al. (1986) made a semi-solid RV-medium by adding agar (MSRV). In comparison to traditional methods this formulation gave more Salmonella-positive results.
The detection principle is based on the motility of Salmonellae to migrate into the semi-solid medium thus forming opaque halos of growth.
The motility of other microorganisms is largely inhibited by selective agents (Magnesium chloride, Malachite green and Novobiocin) and the enhanced incubation temperature of 42 °C.

Preparation
Suspend 15.8 g in 500 ml purified water by heating in a boiling water bath or in a flowing steam until the medium is completely dissolved. Do not autoclave / do not overheat!
Dissolve the lyophilisate of 1 vial MSRV Selective Supplement by adding 1 ml sterile distilled water and add the solution to the medium cooled to 45-50 °C. Mix gently and pour plates.
pH: 5.6 ± 0.2 at 25 °C.
The prepared medium is clear and bright-blue and can be stored in the refrigerator at +2 °C to +8 °C for up to 2 weeks.
The plates must be well dried before use (minimum 1 h at room-temperature).

Experimental Procedure

1.	Enrich the sample material in Buffered Peptone Water (Incubation: 16-20 h at 42 °C).
2.	Incubate 3 drops (0.1 ml) of the pre-enrichment culture in three different spots on the surface of the MSRV medium plates.
3.	Inoculate the plates aerobically in an upright position for no longer than 24 h at 42 °C.

Evaluation
Motile microorganisms show a halo of growth originating from the inoculation spot. For the confirmation of Salmonella further biochemical and serological tests are recommended.

Quality control

Test strains	Growth	Motility zone
Salmonella typhimurium ATCC 14028	good / very good	20 mm
Salmonella enteritidis ATCC 12076	good / very good	20 mm
Citrobacter freundii ATCC 8090	none
Pseudomonas aeruginosa ATCC 27853	none

Typical Composition (g/liter)
Tryptose 4.59; casein hydrolysate 4.59; sodium chloride 7.34; potassium dihydrogen phosphate 1.47; magnesium chloride anhydrous 10.93; malachite green 0.037; agar-agar 2.7.

Literature

De SMEDT et al.: Rapid Salmonella Detection in Foods by Motility Enrichment on a Modified Semi-Solid Rappaport-Vassiliadis Medium. J. Food Protect. Vol. 49, 7; 510-514 (1986).
De SMEDT, a. BOLDERDIJK, R.F.: Dynamics of Salmonella Isolation with Modified Semi-Solid Rappaport-Vassiliadis Medium. J. Food Protect. Vol. 50, 8; 658-661 (1987).

Salmonella typhimurium