A comparison of the original Rappaport medium (R medium) and the Rappaport–Vassiliadis medium (RV medium) in the isolation of salmonellae from meat products

Abstract

SUMMARYThe Rappaport–Vassiliadis enrichment medium (RV medium)in 10 ml quantities (RV/43 °C, 10 ml) inoculated with 0·1 ml of pre-enrichment medium (P medium) was found more efficient in the isolation of salmonellae from 409 pre-enriched samples (mainly meat products), than the original Rappaport medium incubated at 43 °C (R/43 °C) and the RV medium in 5 ml quantities (RV/43 °C, 5 ml) inoculated with 0·01 ml of P medium (P< 0·001, in both instances). Therefore, the inoculum from pre-enriched foods should not be less than 0·l ml in 10 ml of RV medium.The RV/43°, 10 ml was also better (P< 0·01) in detecting samples containing salmonellas than the original Rappaport medium incubated at 37 °C (R/37 °C, 10 ml) and the modification R25 of R medium incubated at 37 °C. The R25 modification was used in 10 ml quantities (R25/37 °C, 10 ml) inoculated with 0·1 ml of P medium and in 5 ml quantities (R25/37°, 5 ml) inoculated with 0·01 ml of P medium. The last two R25 procedures were of the same efficiency in isolating salmonellas from meat products.