WGS of S. argenteus food isolates. S. argenteus food isolates

Staphylococcal Enterotoxins (SE) preformed in food are the causative agents of staphylococcal food poisoning outbreak (SFPO). In this study we in depth characterized two coagulase-positive non-pigmented staphylococci involved in two independent SFPO cases occurred in France. Both isolates were identified as Staphylococcus argenteus by means of whole genome sequencing. The genomes were analysed for the presence of se genes, whose expression was determined in laboratory medium and, for the first time, in artificially contaminated milk samples by using liquid chromatography-mass spectrometry and ELISA methods. From a collection of publicly available genomes, we performed an unprecedented systematic investigation of the complete se gene set of S. argenteus, including variants and pseudogenes. The most prevalent genes were sex, followed by sel26, sel27 and sey. The egc cluster was less frequent and mostly carried a dysfunctional seg gene. Our results allowed to better clarify the enterotoxigenic properties of S. argenteus, and will help improving the characterization of SE during SFPO investigation and monitoring S. argenteus as an emerging foodborne pathogen.