Next day Salmonella spp. detection method based on real-time PCR for meat, dairy and vegetable food products.
The microbiological standard for detection of Salmonella relies on several cultural steps and requires more than 5 days for final confirmation, and as consequence there is a need for an alternative rapid methodology for its detection. The aim of this study was to compare different detection strategies based on real-time PCR for a rapid and sensitive detection in an ample range of food products: raw pork and poultry meat, ready to eat lettuce salad and raw sheep milk cured cheese. Three main parameters were evaluated to reduce the time and cost for final results: the initial sample size (25 and 50 g), the incubation times (6, 10 and 18 h) and the bacterial DNA extraction (simple boiling of the culture after washing the bacterial pellet, the use of the Chelex resin, and a commercial silica column). The results obtained demonstrate that a combination of an incubation in buffered peptone water for 18 h of a 25 g-sample coupled to a DNA extraction by boiling and a real-time PCR assay detected down to 2-4 Salmonella spp.CFU per sample in less than 21 h in different types of food products. This RTi-PCR-based method is fully compatible with the ISO standard, providing results more rapidly and cost-effectively. The results were confirmed in a large number of naturally contaminated food samples with at least the same analytical performance as the reference method.
Subdirección de Investigación y Tecnología, Instituto Tecnológico Agrario de Castilla y León (ITACyL), Carretera de Burgos Km, 119 Valladolid, Spain; Microbiology Section, Faculty of Sciences, University of Burgos, Plaza Misael Bauñuelos s/n, 9001 Burgos, Spain. Electronic address: rodlazda@gmail.com.
David
D
Rodriguez-Lazaro
Subdirección de Investigación y Tecnología, Instituto Tecnológico Agrario de Castilla y León (ITACyL), Carretera de Burgos Km, 119 Valladolid, Spain.
Patricia
P
Gonzalez-García
Istituto Superiore di Sanità, Veterinary Public Health and Food SafetyDepartment, Viale Regina Elena 299, 00161 Rome, Italy.
Elisabetta
E
Delibato
Subdirección de Investigación y Tecnología, Instituto Tecnológico Agrario de Castilla y León (ITACyL), Carretera de Burgos Km, 119 Valladolid, Spain.
Dario
D
De Medici
Department of Food Science and Technology, University of Cordoba, Campus de Rabanales, Edificio Darwin 14014, Córdoba, Spain.
Rosa Maria
RM
García-Gimeno
Department of Food Science and Technology, University of Cordoba, Campus de Rabanales, Edificio Darwin 14014, Córdoba, Spain.
Antonio
A
Valero
Subdirección de Investigación y Tecnología, Instituto Tecnológico Agrario de Castilla y León (ITACyL), Carretera de Burgos Km, 119 Valladolid, Spain.
Marta
M
Hernandez
D000818:Animals; D002611:Cheese / Q000382:microbiology*; D004269:DNA, Bacterial / Q000032:analysis; D005516:Food Microbiology / Q000379:methods*; D018545:Lactuca / Q000382:microbiology*; D008460:Meat / Q000382:microbiology*; D011200:Poultry; D060888:Real-Time Polymerase Chain Reaction; D012475:Salmonella / Q000235:genetics / Q000302:isolation & purification*; D013552:Swine
D004269:DNA, Bacterial
Detection; Food; Real-time PCR; Salmonella spp.