Purpose: Since the validation in 2011 of the European Screening Method (ESM) for staphylococcal enterotoxins (SEs) detection in food matrices, the EURL for CPS organized three Inter-Laboratory Proficiency Testing Trials (ILPT), i.e. in 2013, 2014 and 2015. The objectives were i) to verify the proficiency of the laboratories from the EURL network in implementing the official SE screening method and ii) to ensure the reliability of the results obtained by the participating laboratories.
Methods: Each ILPT was conducted using the ESM with either the commercial VIDAS SET2 or the RIDASCREEN SET Total detection kit. Eight food matrices were used for these ILPT, including cheese, freeze-dried cheese, tuna, mackerel, roast chicken, ready to eat food, milk and pastry. Food samples were spiked with four SE types (i.e. SEA, SEC, SED and SEE) at different concentrations. For each ITLP, homogeneity and stability studies were performed.
Results: The results showed that ILPT samples were homogeneous (RSD < 15%) and stable. Overall, 31 participants from 27 European countries analysed 155 blank and 620 spiked samples. The results obtained allowed evaluation of sensitivity (> 98%) and specificity (100%) of each detection kit (VIDAS SET2 and RIDASCREEN SET Total).
Significance: Adding further to the validation study carried out in 2011, the results of three ILPTs assessed the proficiency of the EURL network and the performance of the ESM on a large number of food matrices and samples.