Relative accuracy, specificity and sensitivity of a 5′ nuclease Real-Time PCR assay for Salmonella detection in naturally contaminated pork cuts

•A Real-Time PCR assay for Salmonella detection in pork cuts was compared to ISO 6579.•Potentially naturally contaminated meat was collected after storage and transportation.•Relative sensitivity, specificity and accuracy were 90, 78.7, and 82.9% respectively.•A very good agreement with a Cohen's kappa value of 0.81 was registered.•The PCR method might be useful for the quick check of meat lots before distribution.

In the present study the relative sensitivity, specificity and accuracy of a Real-Time PCR assay for Salmonella detection in naturally contaminated pork cuts were evaluated in comparison with the ISO 6579:2004 reference culture method. Meat samples were collected from packaging up to the end of shelf life from 10 different lots over a year. The PCR method included an 18 h pre-enrichment step in buffered peptone water, a DNA extraction step, and a final 5′ nuclease Real-Time PCR assay, including an Internal Amplification Control (IAC) and targeting the ttrRSBCA locus. Based on the analysis of 480 sub-units (three sub-units for each sample), the relative sensitivity, specificity and accuracy of the Real-Time PCR assay were 90, 78.7, and 82.9% respectively, corresponding to a Cohen's kappa value of 0.81 (very good agreement). These results suggest the PCR method as a rapid and accurate method for the quick check of meat lots before distribution. The ISO reference method might be applied only on positive Real-Time PCR samples for confirmatory and isolation purposes, mandatory in epidemiological investigations.