Recovery of Salmonella from High-Moisture Foods by Abbreviated Selective Enrichment

Abstract

Five high-moisture foods were used to evaluate both the effect of a 6 h, rather than the standard 24 h, selective enrichment incubation period, and the efficiency of Rappaport-Vassiliadis (RV) medium relative to the use of selenite cystine (SC) and tetrathionate (TT) broths for the recovery of Salmonella. Cheese and lettuce were artificially inoculated with a pool of two serotypes, whereas the other foods were naturally contaminated. Significantly higher numbers of Salmonella-positive test portions were obtained at 24 h with the following food and media combinations: cheese (TT and RV media), lettuce (SC, TT, and RV media), raw chicken (RV medium), and pork sausage (SC, TT, and RV media). There were no significant differences between the two incubation periods in recovery of Salmonella from turkey. Overall, more Salmonella-positive test portions were obtained from samples of lettuce, chicken, and pork sausage selectively enriched in RV medium than in SC or TT broths. The results of this study indicate that not all high-moisture foods can be selectively enriched for 6 h without a significant loss in recovery of Salmonella. RV medium was superior to SC and TT broths for recovery of Salmonella from some meats and was at least as productive in its recovery from the other high-moisture foods tested.

Production and caracterization of monoclonal antibodies for the detection of Salmonella enterica in chicken meat

“…These protocols serve to inhibit microbial competitors while favours Salmonella growth (24,26). However, it has been shown that many of these protocols can affect negatively the sensitivity of the ELISA, increasing the number of false negatives (1). In this study we were able to show that the use of an enrichment protocol with a reduced incubation time does not affect the sensitivity of the ELISA with MAb 424H.…”

Improved culture methods for isolation of Salmonella organisms from swine feces

“…As confirmed the results of our study, use of SC broth results in a lower diagnostic sensitivity than the use of MSRV plates and TTN broth. 2,8 In our study, comparison of the use of TTN broth with that of MSRV plates and SC broth indicates that the use of TTN broth and MSRV plates results in significantly different diagnostic sensitivities for Salmonella organisms (0.57 and 0.64, respectively). However, Proteus spp can be suppressed by novobiocin.…”

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S almonella organisms are major food-borne pathogens, and bacteriologic cultures of fecal samples from subclinically infected herds provide the established protocol for detection and isolation of Salmonella organisms. 2 The purpose of the study presented here was to compare the diagnostic sensitivity and detection limit of 3 alternative culture methods or protocols with the established ISO protocols.

Materials and MethodsSample collection-From pens of herds of naturally infected pigs, fecal samples were collected into 50-ml plastic jars. This has increased the interest in rapid and cost-effective culture methods.

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“…2 The purpose of the study presented here was to compare the diagnostic sensitivity and detection limit of 3 alternative culture methods or protocols with the established ISO protocols. Furthermore, the media must have a composition that favors Salmonella organisms and suppresses the growth of strong competing bacterial flora found in feces.…”

Important Aspects of Salmonella in the Poultry Industry and in Public Health

“…Suggested protocols also vary with the substrate: Kafel (l981) suggested the use of anaerobic lactose broth, followed by selection in tetrathionate brilliant green broth and plating on brilliant green agar, in the analysis of fish meal. Allen et al (1991) reported that the sensitivity of Rappaport Vassiliadis medium depended on the substrate in the detection of Salmonella spp. in high moisture foods, compared with tetrathionate or selenite cystine broth.…”