Evaluation of culture, ELISA and PCR assays for the detection of Salmonella in seafood

Abstract

Aims: The study evaluated the efficiency of culture, enzyme-linked immunosor-bent assay (ELISA) and polymerase chain reaction (PCR) assays for the detec-tion of Salmonella in naturally contaminated seafood.Methods and Results: In this study, 215 seafood samples comprising fish,shrimp, crab, clam, mussel, oyster, squid, cuttlefish and octopus from fish mar-ket of Cochin (India), were compared by culture, ELISA and PCR methods.Bacteriological Analytical Manual (BAM), U.S. Food and Drug Administration(USFDA) method was followed for culture assay, and Salmonella Tek, a com-mercial sandwich ELISA kit, was used for ELISA assay. Salmonella-specific PCRassay was developed for 284 bp Salmonella-specific invA gene amplicon. PCRassay exhibited 31Æ6% seafood positive for Salmonella followed by ELISA(23Æ7%) and culture method (21Æ3%). There was fair to excellent agreementbetween culture, ELISA and PCR assays (kappa coefficient values ranging from0Æ385 to 1Æ0) for different seafood samples.Conclusion: The investigation revealed the greater concordance between cultureand ELISA methods for seafood. Among the three methods, PCR assay wasmost sensitive. Lower detection rate with culture and ELISA assays could beattributed to greater sensitivity of the PCR method in the detection of Salmo-nella in seafood.Significance and Impact of the Study: We propose the incorporation of dualtests based on different principle and procedure for the routine analysis of Sal-monella in seafood.