Wednesday, May 11, 2016
Megaron Athens International Conference Center
Angelo Romano, Laboratorio Controllo Alimenti - Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Torino, Italy
Guerrino Macori, Laboratorio Controllo Alimenti - Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Torino, Italy
Daniela Adriano, Laboratorio Controllo Alimenti - Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Torino, Italy
Daniela Manila Bianchi, Laboratorio Controllo Alimenti - Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Torino, Italy
Silvia Gallina, Italian NRL for CPS - Laboratorio Controllo Alimenti - Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d’Aosta, Torino, Italy
Monica Gramaglia, Laboratorio Controllo Alimenti - Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Torino, Italy
Fabio Zuccon, Italian NRL for CPS - Laboratorio Controllo Alimenti - Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d’Aosta, Torino, Italy
Lucia Decastelli, Italian NRL for CPS - Laboratorio Controllo Alimenti - Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d’Aosta, Torino, Italy
Introduction: Staphylococcus aureus strains produce several
enterotoxins (SEs) with demonstrated emetic activity, which are a major cause of food poisoning occurring after ingestion of contaminated foods. The concentrations of SEs able to produce symptoms can be lower than the limit of detection (LOD) of methods used for SEs detection in food control laboratory. For this reason, a concentration step is usually performed, before the detection assay. To date, the dialysis concentration protocol is used in accredited laboratories for official controls on foods. The evaluation of different extaction/concentration methods in various food matrices will possibly reduce performing time and improve LOD of SEs.
Purpose: Our aim is to evaluate new protocols for extraction/concentration of SEs in order to increase the performance of detection step and to reduce the response-time of laboratory.
Methods: Three different proteins extraction and/or concentration methods were tested in parallel with the dialysis concentration method. The alternative protein precipitation protocols were: trichloroacetic acid (TCA), gel phosphate buffer (TGF), and Tris Glycine Beef Extract with poliethylenglycol (TBGE/PEG). Each concentration protocol was used on milk and water samples contaminated with SEB from Staphylococcus aureus (SIGMA-ALDRICH). Milk samples were spiked at concentrations from 50 ng/ml to 1 ng/ml and water samples from 50 ng/ml to 0,1 ng/ml. After extraction/concentration, all samples were tested with RIDASCREEN SET Total ELISA kit.
Results: The TCA protein precipitation showed a lower efficiency compared with the other methods and was dismissed for further tests. Our results, based on the ELISA test, confirm that other investigated extaction/concentration methods are suitable for improving SEs detection step and can be the object of further investigation.
Significance: The dialysis protocol is to date recognized as the more suitable method for SEs concentration. Due to its long incubation period, efforts are required to evaluate new and less time consuming methods.
