Isolation of Salmonella from Fluid Milk with the Use of Rappaport-Vassiliadis Medium

The performances of Rappaport-Vassiliadis (RV) medium and tetrathionate brilliant green broth (TT) for the detection of salmonellae in pasteurized fluid whole milk, artificially contaminated, were compared. The RV medium was found to be more sensitive and more selective than the TT medium, as far as Salmonella typhimurium was concerned. From the 100 samples contaminated with S. typhimurium only, 97 were found positive witb RV medium, while 86 were found positive with TT medium (P<0.001). From the 100 samples contaminated with S. typhimurium plus gram-negative competing organisms, 79 were found positive with RV medium, while only 41 with TT medium (P<10). The mean values of growth of competing organisms in RV medium after 24 and 48 h of incubation at 43°C were 0.81 and 0.92, respectively, while the corresponding values in TT medium were 1.81 and 1.87.