Detection of Listeria monocytogenes in food using a combined enrichment/real-time PCR method targeting the prfA gene

Res Microbiol. 2006 Oct;157(8):763-71. doi: 10.1016/j.resmic.2006.03.003. Epub 2006 Apr 3.

Abstract

A combined enrichment/real-time PCR method for the detection of Listeria monocytogenes is presented. The method is based on a conventional PCR assay targeting the prfA gene, which has been validated and suggested as an international standard PCR method for identifying L. monocytogenes in food. This real-time PCR assay includes an internal amplification control. Inclusivity and exclusivity were 100% each when testing 100 L. monocytogenes isolates, 30 Listeria spp. isolates other than L. monocytogenes, and 29 non-Listeria isolates. The theoretical detection limit was one copy of the target gene per PCR reaction and the practical detection limit was about 5 copies per PCR. Using the combined enrichment/real-time PCR method, 7.5 CFU/25 ml of artificially contaminated raw milk, and 9, 1, and 1 CFU/15 g of artificially contaminated salmon, pâté, and green-veined cheese, respectively, were detected. When analyzing 76 naturally contaminated food samples of various types and comparing the results with the ISO 11290-1 standard method, the relative accuracy was 96%, the relative specificity 100%, and the relative sensitivity, 76.9%.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Typing Techniques
  • Cheese / microbiology
  • Food Microbiology*
  • Genes, Bacterial
  • Listeria monocytogenes / genetics
  • Listeria monocytogenes / isolation & purification*
  • Milk / microbiology
  • Peptide Termination Factors / analysis*
  • Polymerase Chain Reaction
  • Salmon / microbiology

Substances

  • Peptide Termination Factors