Rapid, specific detection of Salmonella Enteritidis in pooled eggs by real-time PCR

J Food Prot. 2004 May;67(5):864-9. doi: 10.4315/0362-028x-67.5.864.

Abstract

An assay was developed for the specific detection of Salmonella Enteritidis in eggs with the use of an application of the fluorogenic 5' nuclease assay (TaqMan). In this assay, a segment of the gene sefA specific to Salmonella group D strains such as Salmonella Enteritidis was used. The amplification of the target gene products was monitored in real-time by incorporating a fluorescent dye-labeled gene-specific probe in the PCR reaction. This method correctly detected and distinguished Salmonella Enteritidis from nearly 50 of non-group D Salmonella and other non-Salmonella strains. Detection of the sefA gene was linear for DNA extracted from approximately 10(2) to 10(9) CFU/ml in phosphate-buffered saline and 10(3) to 10(8) CFU/ml in raw egg. In two trials, when applied to detection of Salmonella Enteritidis in homogenized egg pools and compared with conventional culture methods, the newly developed PCR method yielded a 100% correlation with results obtained by a conventional culture method. However, the PCR method required only 2 days, compared to the 5 days required by the culture method. The sensitivity of this assay was approximately less than 1 CFU/600 g of egg pool. The real-time PCR assay proved to be a rapid, highly sensitive test for detection and quantification of low concentrations of Salmonella Enteritidis in egg samples.

MeSH terms

  • Animals
  • Colony Count, Microbial
  • DNA, Bacterial / analysis
  • Eggs / microbiology*
  • Fimbriae Proteins
  • Food Contamination / analysis*
  • Food Microbiology
  • Gene Amplification
  • Genes, Bacterial
  • Polymerase Chain Reaction / methods
  • Salmonella enteritidis / isolation & purification*
  • Sensitivity and Specificity
  • Time Factors

Substances

  • DNA, Bacterial
  • sefA protein, Salmonella enteritidis
  • Fimbriae Proteins