RAPPAPORT VASSILIADIS SOYA BROTH (RVS BROTH) used for selective enrichment of Salmonellae. The composition of the medium was developed by “Rappaport” following the observation that Salmonella was more resistant to hypertonic media than most other enterobacteria. In his experiments, Rappaport showed that magnesium chloride was the most effective of all the salts tested. Finally, van Schothorst and Renaud modified Rappaport Vassiliadis Broth by replacing the Casein peptone with a Soya peptone as the carbon and nitrogen sources for general growth requirements. By incorporating a Monopotassium phosphate buffer into the formula, resulting in a greater stability of the medium over time. Selectivity of the medium was increased still further by the addition of malachite green. Malachite Green is inhibitory to organisms other than Salmonella spp. The low pH of the medium, combined with the presence of Malachite Green and Magnesium Chloride, select for the highly resistant Salmonella spp. Sodium chloride supplies essential electrolytes for transport and osmotic balance.
Transfer 0.1 ml of inoculum into a tube of 10 ml of medium prepared (respect the 1:100 ratio). Inoculum generally constitutes a pre-enrichment medium: Buffered Peptone Water (TM 307) - Incubate. and incubate at 35°C for 16 – 20 hours. Carry out isolation in several selective media for Salmonella sp., with a platinum loop. Inoculate 0.1 ml of the pre-enrichment Buffered Peptone Water to 10 ml of Rappaport - Vassiliadis Soya Peptone Broth and incubate at 41.5 ± 0.5°C for 21 - 27 hours. Subculture onto confirmatory medium, including XLD Agar at 35 ± 2°C. Examine for growth after 18 – 24 hour incubation.