The detection of Staphylococcus serves as indicator of microbial food contaminations through improper personal hygiene in the food process. However, the detection of the Staphylococcus-released enterotoxins (SE) provoking vomiting is important to evaluate the safety of foodstuff.

In this study we evaluated two routine type tests of SE. The newly established mass spectrometry (MS)-based test was compared with the commercially available and food-safety-certified analysis of SE, which is an immuno-based ELISA. In a second approach, foodborne isolates of S.aureus were genome sequenced and the presence or absence of SE genes, termed se, was determined serving as basis for the evaluation of the toxin tests.

In essence, severalS.aureus strains carried the genes seb and sec , which encode the genetic information for the production of the well-characterised SE toxin types SEB, SEC. In S.aureus  culture supernatants where SEB and SEC were produced, the novel MS-based positive signals were confirmed by the standard immune-based positivity. Further studies, showed that the here established MS-based test carries advantages over the commercial methods. It showed less false positive results and it was quicker. The discovered limitations of the commercial test underline that future studies are warranted in order to establish a reliable test of the SE toxins. The mass spectrometry-based method developed at HES-SO Sion provides a promising approach of advanced SE-quicktesting. This will ultimately lead to improved food safety.

The current project was run in good complementarity between different institutes of HES-SO. The Geneva-based hepia institute analysed the Staphylococcus enterotoxin genes (se) by sequencing multiple S.aureus strains genomes. The Sion-based Life Technologies institute established the novel MS-based SE-test of the produced toxins. Collaborations with the University of Lyon (F), the University of Bern, Agrascope and BAG institutes (Bern), and the Spiez Toxicology laboratories also resulted from this project. Furthermore, promising interactions with the in vitro Diagnostics platform from Swiss Biotechnet including industrial partners, like Mabritec AG, were launched during this project. The SE-Quicktest has already and continuous to be published in scientific articles [Crovadore et al. 2015][Tonacini et al. 2016 in prep.].


Bruno Schnyder

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