Real-time PCR for the detection of Salmonella spp. in food: An alternative approach to a conventional PCR system suggested by the FOOD-PCR project.
A real-time PCR assay using non-patented primers and a TaqMan probe for the detection and quantification of Salmonella spp. is presented. The assay is based on an internationally validated conventional PCR system, which was suggested as a standard method for the detection of Salmonella spp. in the FOOD-PCR project. The assay was sensitive and specific. Consistent detection of 9.5 genome equivalents per PCR reaction was achieved, whereas samples containing an average of 0.95 genome equivalents per reaction were inconsistently positive. The assay performed equally well as a commercially available real-time PCR assay and allowed sensitive detection of Salmonella spp. in artificially contaminated food. After enrichment for 16 h in buffered peptone water (BPW) or universal pre-enrichment broth (UPB) 2.5 CFU/25 g salmon and minced meat, and 5 CFU/25 g chicken meat and 25 ml raw milk were detected. Enrichment in BPW yielded higher numbers of CFU/ml than UPB for all matrices tested. However, the productivity of UPB was sufficient, as all samples were positive with both real-time PCR methods, including those containing less than 300 CFU/ml enrichment broth (enrichment of 5 CFU/25 ml raw milk in UPB).
Institute of Milk Hygiene, Milk Technology, and Food Science, Department of Veterinary Public Health and Food Science, University of Veterinary Medicine, Veterinaerplatz 1, A-1210 Vienna, Austria. ingeborg.hein@vu-wien.ac.at
Ingeborg
I
Hein
Gabriele
G
Flekna
Martina
M
Krassnig
Martin
M
Wagner
D000818:Animals; D002417:Cattle; D002645:Chickens; D003470:Culture Media; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005516:Food Microbiology; D008460:Meat / Q000382:microbiology*; D008892:Milk / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D012474:Salmon; D012475:Salmonella / Q000235:genetics / Q000302:isolation & purification*; D012478:Salmonella Food Poisoning / Q000382:microbiology* / Q000517:prevention & control; D012680:Sensitivity and Specificity
D003470:Culture Media; D004269:DNA, Bacterial