Rappaport Vassiliadis (R.V. ) Single Component Enrichment Broth

LAB 86

Introduction

Rappaport Vassiliadis Broth (R10 modification) was born out of a long series of experiments carried out to determine the correct levels of malachite green and magnesium chloride that would allow Salmonella to multiply freely yet still inhibit the other enteric organisms.

This formulation has been shown to be superior to Mueller Kauffmann and Selenite Broth for the isolation of Salmonella from meat products.

The development work carried out on the formulation shows that it is extremely efficient in detecting small numbers of Salmonella in heavily contaminated products. This formulation is very hygroscopic and will produce a slight exothermic reaction when mixed with water.

Method for reconstitution

Weigh 26.8 grams powder, disperse in 1 litre of deionised water, swirl to mix, when dissolved dispense in 10ml volumes in screw capped bottles and sterilise by autoclaving at 115˚C for 15 minutes.

Appearance: Clear, green fluid.

pH: 5.2 ± 0.2

Minimum Q.C. organisms: E. coli (inhibited) NCIMB 50034 S. typhimurium NCIMB 50076

Storage of Prepared Medium: Capped container - 6 months at 2-8˚C

Inoculation: From pre-enrichment broth in the proportions of 1-part inoculum to 99 parts R.V. Broth. Sub-culture onto either XLD Agar, M.L.C.B. Agar or other salmonella selective agars.

Incubation: 41.5 ± 0.5˚C for 24 hours (incubator) or 42 ± 0.1˚C for 24hrs (water bath).

References

Vassiliadis, P. , (1983) The Rappaport Vassiliadis (R.V.) Enrichment Medium for the Isolation of salmonellas: An overview J. Appl. Bacteriol. 56 69-76.

Vassiliadis, P. , Mavromatti, CH. Efstratiou, M. and Chronas, G. (1985). A note on the stability of Rappaport-Vassiliadis Enrichment Medium J. Appl. Bacteriol. 59 143-145.

Bolton, F.G., Preston, P.H.L. Personal communication.

Int. J. Food Micro. Pharmacopoeia of culture media for Food Microbiology.

Peterz, M., Wiberg, C., and Norberg, P. 1989. The effect of incubation temperature and magnesium chloride concentration on growth of Salmonella in home-made and in commercially available dehydrated Rappaport-Vassiliadis broths.