P3-08 Comparison of Two Commercial Real-Time PCR Systems with Culture Methods for the Detection of Salmonella spp. in Environmental and Fecal Samples of Poultry

Wednesday, July 25, 2012
Exhibit Hall (Rhode Island Convention Center)
Charlotte Lindhardt, Merck Millipore, Darmstadt, Germany
Dagmar Sommer, Justus-Liebig-University , Giessen, Germany
Michael Lierz, Justus-Liebig-University , Giessen, Germany
Joerg Slaghuis, Merck Millipore, Darmstadt, Germany
Holger Schoenenbruecher, Merck Millipore, Darmstadt, Germany
Introduction: Salmonella are an important cause for severe human gastroenteritis after consumption of contaminated poultry products, especially eggs and meat. European regulations are aiming to reduce Salmonella prevalence in primary production of poultry to less than 1%.

Purpose: The purpose of this study was to evaluate the foodproof® Salmonella detection kit for the detection of Salmonella in sample types being mandatory for monitoring primary production such as boot socks, feces, feed and dust.

Methods: The study compared the efficiency of the foodproof® Salmonella detection kit and Bax® PCR Assay Salmonella system with standardized culture methods (EN ISO 6579:2002 – Annex D) for the detection of Salmonella spp. in poultry samples. For evaluation four sample matrices (feed, dust, boot swabs, feces) directly from poultry flocks as well as artificially spiked samples of the same matrices were used. All samples were tested first for Salmonella spp. using culture methods as the gold standard. Furthermore, all methods were evaluated in an annual ring-trial of the National Salmonella Reference Laboratory of Germany.

Results: Salmonella detection in the matrices feed, dust and boot swabs led to comparable results of both PCR systems whereas the results from feces differed markedly. Furthermore, the quality, especially the freshness, of the fecal samples had an influence on the sensitivity of the real-time PCR and culture methods results. In fresh fecal samples an initial spiking level of 100 CFU/25 g Salmonella Enteritidis was detected. Dry fecal samples allowed the detection of 14 CFU/25 g.  Both real-time PCR protocols appear to be suitable for the detection of Salmonella spp. in all four matrices.

Significance: RT-PCR reduces time to result to two days only compared to classical culture enabling, e.g., faster restocking or product release.