Relative effectiveness of selenite cystine broth, tetrathionate broth, andRappaport-Vassiliadis medium for the recovery of Salmonella spp. from foods with a low microbial load

The relative effectiveness of Rappaport-Vassiliadis (RV) medium, selenite c ystine (SC) broth, and tetrathionate (TT) broth for the recovery of Salmone lla spp. from foods with a low microbial load was determined. RV medium mad e from its individual ingredients and incubated at 42 degrees C was compare d with a commercial preparation of SC broth, incubated at 35 degrees C, and TT broth incubated at 35 and 43 degrees C, for the recovery of Salmonella spp. Twenty-one artificially contaminated food types that included dairy fo ods, spices, and egg products, as well as other low-microbial-load foods, w ere analyzed. The foods were inoculated with single Salmonella serovars at target levels ranging from 0.04 to 0.4 CFU/g. No significant differences (P less than or equal to 0.05) among the selective enrichment broths for the recovery of Salmonella spp. from 18 of the foods were observed. Significant ly fewer Salmonella-positive test portions of gelatin, guar gum, and nonfat dry milk were recovered with RV medium than with SC broth incubated at 35 degrees C and TT broth incubated at 35 and 43 degrees C. IT broth incubated at 35 degrees C recovered the greatest number of Salmonella-positive test portions. For the recovery of Salmonella spp. from foods with a law microbi al load, it is recommended that TT broth incubated at 35 degrees C and RV m edium incubated at 42 degrees C be used.