Collaboratrici e collaboratori

Beside the infection in human beings and animals, Staphylococcus aureus can produce different enterotoxins in food. These enterotoxins can cause vomiting and diarrhea, often involving many people and causing so called staphylococcal foodborne outbreaks (SFPO). To date a lot of SFPO are of weak evidence. One reason for this could be, that currently only five, so called classical enterotoxins, out of 26 known staphylococcal enterotoxins can be analyzed using commercially available kits. A subset of the non-classical enterotoxins (seg, sei, sem, sen, seo and seu) is located on the same enterotoxin gene cluster (egc) which is part of the S. aureus genomic island vSaβ. These enterotoxins have been described as likely being involved in SFPOs. New tools such as whole genome sequencing and new methods for enterotoxin measurement are needed in order to be able to analyse the S. aureus strains and their enterotoxins and, consequently, being able to predict the en-terotoxin production based on genome data. This was the main aim of this work. In order to do so, the egc enterotoxins were studied at genome (seg, sei, sem, sen, seo, and seu), at mRNA (seg, sei, sem, sen, seo), and at protein level (SEG and SEI). We demonstrate that the in vitro production of SEG and SEI can be predicted based on the vSaβ-type and the clonal complex (CC) of a strain. Furthermore, the vSaβ-type/CC enables the prediction of the source of an egc-positive SFPO strain (animal or human derived). Enterotoxin production (SEG and SEI) under stress conditions was also tested, showing that common salt con-centrations and temperature stress, mimicking conditions found in food production, seem not to affect the pro-duction of egc enterotoxins SEG and SEI. With the present work a contribution can be given to a better understanding of the involvement of egc enterotoxins producing S. aureus strain in SFPOs. In addition, the results also give a first insight into the conditions and limits of egc enterotoxin production and a first indication in how they have the ability to be produced in food production and storage.