Development and validation of the Standard method EN ISO 19020 - microbiology of the food chain - Horizontal method for the immunoenzymatic detection of staphylococcal enterotoxins in foodstuffs

Abstract

In the frame of the CEN Mandate M/381 from the European Commission to CEN (European Committee for Standardization), a method for the detection of staphylococcal enterotoxins in foodstuffs has been developed, validated and standardized. An extraction procedure based on dialysis concentration followed by an immuno-enzymatic detection has been defined. In addition, performance criteria (minimum values of sensitivity, specificity and level of detection) to be achieved by the commercially available immuno-enzymatic kits that could be used to detect staphylococcal enterotoxins in food matrices, were developed. A 2-stage validation study was conducted: The first stage aimed at selecting the commercial kits to be included in the second stage, which consisted in an interlaboratory study, using eight matrices covering five food categories (ready-to-eat food, meat products, milk products, dessert and fish). Results showed that two detection kits included in the study met the pre-defined performance criteria. The implementation of dialysis concentration step increased significantly the sensitivity of the method. The method developed allowed to achieve the Benchmark Dose lower limit (BMD₁₀) estimated at 6.1 ng. In 2019, finally, the European Commission recognized this standard as the European Union reference method for the detection of staphylococcal enterotoxins in food.

Keywords: Detection; Food; Microbiological methods; Sensitivity; Specificity; Staphylococcal enterotoxins; Validation.