Detection of Listeria monocytogenes in food using a combined enrichment/real-time PCR method targeting the prfA gene.
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%.
Rossmanith
Peter
P
Institute of Milk Hygiene, Milk Technology, and Food Science, Department of Veterinary Public Health and Food Science, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria.
Krassnig
Martina
M
Wagner
Martin
M
Hein
Ingeborg
I
D000818:Animals; D015373:Bacterial Typing Techniques; D002611:Cheese / Q000382:microbiology; D005516:Food Microbiology; D005798:Genes, Bacterial; D008089:Listeria monocytogenes / Q000235:genetics / Q000302:isolation & purification*; D008892:Milk / Q000382:microbiology; D010454:Peptide Termination Factors / Q000032:analysis*; D016133:Polymerase Chain Reaction; D012474:Salmon / Q000382:microbiology
D010454:Peptide Termination Factors