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Material Safety Data Sheet

Required Products

Organisms

Organisms this product works with:

Dehydrated Culture Media

MODIFIED SEMI-SOLID RAPPAPORT VASSILIADIS (MSRV) MEDIUM BASE

Code: CM0910

A semi-solid medium for the detection of motile Salmonella species from food and environmental samples.

Typical Formula*

gm/litre

Tryptose

4.59

Casein hydrolysate

4.59

Sodium chloride

7.34

Potassium dihydrogen phosphate

1.47

Magnesium chloride (anhydrous)

10.93

Malachite green oxalate

0.037

Agar

2.7

pH 5.4 ± 0.2 @ 25°C

 
* Adjusted as required to meet performance standards

MSRV SELECTIVE SUPPLEMENT

Code: SR0161

Vial contents (each vial is sufficient for 500ml of medium)

per vial
per litre

Novobiocin

10.0mg

20.0mg

Directions
Suspend 15.8g of MSRV Medium Base in 500ml of distilled water. Bring to the boil with frequent agitation.
DO NOT AUTOCLAVE. Cool to 50°C and aseptically add the contents of 1 vial of MSRV Selective Supplement SR0161E reconstituted with 2ml of sterile distilled water. Mix well and pour into sterile Petri dishes. Air dry at room temperature for at least one hour. (Plates may be air-dried overnight prior to storage at 2-8°C.)

Description
Modified Semi-solid Rappaport Vassiliadis (MSRV) Medium is based on the formulation described by De Smedt et al. which has been shown to detect more Salmonella-positive samples than the traditional enrichment procedures1,2. Further collaborative studies have confirmed these findings3,4.

Motility enrichment on MSRV Medium has been designed as a simple, sensitive method for the isolation of salmonellae from food and environmental samples. The efficiency of the medium is based on the ability of salmonellae to migrate through the selective medium ahead of competing motile organisms, thus producing opaque halos of growth.

Further tests can be carried out directly from the migrated culture with the inoculum being taken from the edge of the growth. Oxoid Salmonella Latex Test FT0203 or DR1108 may be used for serological confirmation of Salmonella species.

The medium is not suitable for the detection of non-motile strains of Salmonella (incidence5. (Figures obtained from records of the Department of Enteric Pathogens, Central Public Health Laboratory, Colindale, London. Dr. B. Rowe, Personal Communication, 1988.)

Technique
1. Inoculate up to three drops (ca. 0.1ml) of the pre-enrichment culture (after incubation for 16-20 hours) in separate, evenly spaced spots on the surface of the MSRV Medium plates.
2. Incubate the plates in an upright position at 42°C for up to 24 hours. (Care should be taken not to exceed 24 hours.)
3. Examine the plates for motile bacteria which will be shown by a halo of growth originating from the inoculation spot.
4. Subcultures can be taken from the outside edge of the halo to confirm purity and for further biochemical and serological tests.

De Smedt6 reported that if MSRV medium is contained in test tubes and incubation is carried out under anaerobic conditions, visible migration zones are produced in 6 hours enabling Salmonella in foods to be detected in 24 hours.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the selective supplement in the dark at 2-8°C and use before the expiry date on the label.
The prepared medium may be stored for up to 2 weeks at 2-8°C away from the light.

Appearance
Dehydrated medium: Green coloured, free-flowing powder
Prepared medium: Blue coloured semi-solid gel

Quality control

Positive controls:

Expected results

Salmonella poona NCTC 4840

Straw colonies at site of inoculation surrounded by halo of growth

Salmonella enteritidis ATCC® 13076 *

Straw colonies at site of inoculation surrounded by halo of growth

Negative control:

 
Citrobacter freundii ATCC® 8090 * Restricted or no growth
* This organism is available as a Culti-Loop®

Precautions
The basal medium is very hygroscopic. When handling the powder a face mask and gloves must be worn, refer to the material safety data sheet.

References
1. De Smedt J. M., Bolderdijk R., Rappold H. and Lautenschlaeger D. (1986) J. Food. Prot. 49. 510-514.
2. De Smedt J. M., Bolderdijk R. (1987) J. Food. Prot. 50. 658-661.
3. De Zutter L. et al. (1991) Int. J. Food Micro. 13. 11-20.
4. De Smedt J. M. et al. (1991) Int. J. Food Micro. 13. 301-308.
5. Holbrook R., Anderson J. M., Baird-Parker A. C., Dodds L. M., Sawhney D., Struchbury S. H. and Swaine D. (1989) Lett. Appl. Microbiol. 8. 139- 142.
6. De Smedt, J. M. (1998) Abstract 1.5. Int. Symposium - Food borne Pathogens: Detection and Typing. The Hague, The Netherlands 20th-21st April 1998.

 
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