IMS: a new selective enrichment technique for detection of Salmonella in foods

Cudjoe, Kofitsyo S.; Krona, Ragnhild; Olsen, Egil

doi:10.1016/0168-1605(94)90049-3

Cited by 51 publications

(21 citation statements)

References 6 publications

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“…Uneven distribution of salmonellae in the feed sample or in the preenrichment broth may account for some of these conflicting results. Furthermore, strains might not be able to grow in the selective broth or on the agar plates employed (12). It is known that to be able to distinguish between salmonellae and other bacteria growing on selective agar plates, the number of Salmonella cells must be at least 10 4 CFU/ml after the enrichment step (9).…”

Section: Discussionmentioning

confidence: 99%

“…Many sample preparation methods, such as DNA extraction (13), and immunomagnetic separation (12), are laborious and expensive and do not provide the desired template quality. Therefore, there is a need for simple and robust sample preparation methods that take advantage of the use of whole cells instead of DNA before diagnostic PCR can be widely used for routine analysis of feed and food samples.…”

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confidence: 99%

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Rapid and Specific Detection ofSalmonellaspp. in Animal Feed Samples by PCR after Culture Enrichment

Löfström

Knutsson

Axelsson

et al. 2004

Appl Environ Microbiol

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A PCR procedure has been developed for routine analysis of viable Salmonella spp. in feed samples. The objective was to develop a simple PCR-compatible enrichment procedure to enable DNA amplification without any sample pretreatment such as DNA extraction or cell lysis. PCR inhibition by 14 different feed samples and natural background flora was circumvented by the use of the DNA polymerase Tth. This DNA polymerase was found to exhibit a high level of resistance to PCR inhibitors present in these feed samples compared to DyNAzyme II, FastStart Taq, Platinum Taq, Pwo, rTth, Taq, and Tfl. The specificity of the Tth assay was confirmed by testing 101 Salmonella and 43 non-Salmonella strains isolated from feed and food samples. A sample preparation method based on culture enrichment in buffered peptone water and DNA amplification with Tth DNA polymerase was developed. The probability of detecting small numbers of salmonellae in feed, in the presence of natural background flora, was accurately determined and found to follow a logistic regression model. From this model, the probability of detecting 1 CFU per 25 g of feed in artificially contaminated soy samples was calculated and found to be 0.81. The PCR protocol was evaluated on 155 naturally contaminated feed samples and compared to an established culture-based method, NMKL-71. Eight percent of the samples were positive by PCR, compared with 3% with the conventional method. The reasons for the differences in sensitivity are discussed. Use of this method in the routine analysis of animal feed samples would improve safety in the food chain.Salmonellosis is currently a zoonotic disease of considerable magnitude (15). Animal feed is a recognized source of Salmonella enterica for farm livestock and might also act as an indirect cause of infection of people consuming foods of animal origin. Salmonellae can survive for several years in feed (14), and low concentrations have been found to be infective in, for instance, chickens (18). Transmission of salmonellae from feed to animals such as cattle and chickens is well documented (18,22). In several countries, salmonellae have been isolated from animal feed ingredients as well as the final product, of both vegetable and animal origin, with a prevalence of between 0 and 6% (17, 30). The levels of salmonellae in feed are low; D'Aoust and Sewell (14) quantified salmonellae in several kinds of feed ingredients and compound feeds and found the levels to be less than 1 bacterium per g of feed.The established culture-based methods used to detect salmonellae in animal feed are laborious, time-consuming, and often not specific enough. The standard methods used today for analyzing salmonellae involve preenrichment in buffered peptone water (BPW), selective enrichment in RappaportVassiliadis soy broth, plating on selective agar, and subsequent identification by biochemical tests, for example, NMKL-71 (7). The whole procedure takes at least 3 days to complete. Several alternative analysis strategies have been proposed, and PCR in partic...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Rapid and Specific Detection ofSalmonellaspp. in Animal Feed Samples by PCR after Culture Enrichment

Löfström

Knutsson

Axelsson

et al. 2004

Appl Environ Microbiol

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“…Immunomagnetic separation (IMS) has been shown to be a sensitive method for the detection of Salmonella in food samples (Cudjoe et al 1994(Cudjoe et al , 1995Cudjoe and Krona 1997) and automation of IMS (AIMS) has been applied for investigation into a food-borne disease outbreak of Salmonella (Duncanson et al 2003). The Most Probable Number (MPN) procedure has been used for estimating the numbers of Salmonella on poultry carcases and rinses (Jetton et al 1992;Whittemore 1993;Humbert et al 1997) and a combination of MPN and IMS has been used for the enumeration of E. coli O157 in meats (Chapman et al 2001) and in cattle faeces (Fegan et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Quantification and prevalence of Salmonella in beef cattle presenting at slaughter

et al. 2004

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Methods and Results: Automated immunomagnetic separation (AIMS) was used for detection and isolation of Salmonella enriched from cattle faeces. Salmonella were enumerated from positive samples using a combination of the Most Probable Number (MPN) technique and AIMS. A total of 310 faecal samples were tested, 155 were from lot-fed cattle and 155 from grass-fed cattle. Salmonella spp. were isolated from 21 (6AE8%) of the cattle and the prevalence amongst grass-fed cattle (4AE5%) was not significantly different to that found in lot-fed cattle (9%). Counts of Salmonella in positive faeces varied from <3 MPN g)1 of faeces to 2AE8 · 10 3 MPN g )1 and 71% of positive samples had counts <10 MPN g )1 faeces. There was no significant difference in the mean log 10 number of Salmonella in faeces of cattle from each production system. Conclusion: Low numbers of beef cattle were found to shed Salmonella at the time of slaughter and the prevalence and the associated faecal concentrations did not vary significantly with the pre-slaughter production system (grass or lot feeding). The faecal concentration of Salmonella in the majority of faeces was low (<10 MPN g )1 ) with few high concentrations up to 3 · 10 3 MPN g )1 , suggesting there may be a low risk of carcase contamination.Significance and Impact of the Study: Beef cattle do not appear to be a major source of entry of Salmonella into the human food chain and the quantitative information contained in this study can be used in quantitative assessments of the associated risk of human salmonellosis.

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“…Mansfield and Forsythe (7) and Molla et al (8) (11), which reported a poor performance of the IMS method in detecting Salmonella from, respectively, naturally contaminated raw sausages and poultry samples. The use of highly selective plating media can be one of the causes (4), since the selection pressure can make the growth of bacteria linked to the beads more difficult (5).…”

Section: Resultsmentioning

confidence: 99%

Utilization of immunomagnetic separation for detection of Salmonella in raw broiler parts

Ribeiro¹,

Nascimento²,

Cardoso³

et al. 2002

Braz. J. Microbiol.

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This study was conducted aiming to compare the conventional microbiological method to detect Salmonella in broiler parts with the Immunomagnetic Separation method (IMS) followed by plate isolation and also the IMS associated with Rappaport-Vassiliadis broth (RV). The IMS was performed following a pre-enrichment step in buffered peptone water. Sixty-one samples (raw broiler parts) were tested and the results showed that the use of the IMS method alone allowed the isolation of Salmonella in 9 of the tested samples, while the association IMS/ RV detected the agent in 30 samples. The conventional microbiological method was able to isolate the agent in 25 opportunities. These results allowed to conclude that the IMS/RV association presented an increased sensitivity and permitted a better isolation of Salmonella. The conclusion was that other means of isolation, in particular those which do not interfere with the growth of bead bounded Salmonella, should be searched.

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IMS: a new selective enrichment technique for detection of Salmonella in foods

Cited by 51 publications

References 6 publications

Rapid and Specific Detection ofSalmonellaspp. in Animal Feed Samples by PCR after Culture Enrichment

Rapid and Specific Detection ofSalmonellaspp. in Animal Feed Samples by PCR after Culture Enrichment

Quantification and prevalence of Salmonella in beef cattle presenting at slaughter

Utilization of immunomagnetic separation for detection of Salmonella in raw broiler parts

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