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Abstract
A sandwich ELISA assay using monoclonal and polyclonal antibodies against salmonella has been proposed. The activity of the label enzyme (horseradish peroxidase) is measured electrochemically using 3,3′,5,5′ tetramethylbenzidine as substrate. The efficiency and specificity of the method were verified during preliminary studies on various serotypes of Salmonella and other bacteria commonly present in food (E. coli, Klebsiella pneumoniae, Morganella morganii, Citrobacter freundii, Yersinia enterocolitica). The assay was then used to analyse samples of pork, chicken and beef experimentally contaminated with different concentrations of salmonella and samples not experimentally contaminated. Analysis were performed in parallel following the traditional cultural method. The samples were seeded in pre-enrichment broth (buffer peptone water) and amounts were taken at different times and analysed by electrochemical ELISA to determine the minimum incubation time needed to detect salmonella. Results showed that the method was efficient, sensitive and rapid: after only 5 h of incubation in pre-enrichment broth it was possible to detect salmonella in meat experimentally contaminated with low concentrations of salmonella (1–10 cells/25 g).
ACKNOWLEDGMENTS
The authors wish to thank the CNR project “Biotecnologie” for financial support.