Funktionelle Charakterisierung neuer Virulenzfaktoren von Staphylococcus aureus Staphylococcus (S.) aureus is the most common cause of nosocomial infections and the species is becoming increasingly resistant to antibiotics. In contrast about 35% of the healthy population are colonized with S. aureus in the anterior nares. The genetic make up of this species is highly diverse. Mobile genetic elements comprise about 15% of the S. aureus genome. They encode many virulence factors like the 21 different known staphylococcal superantigens (SAgs) highly potent activators of T lymphocytes. Besides their well known causative role in food poisoning and toxic shock syndrome information about SAg involvement in pathogenesis is limited. On the other hand the human host and its immune response are also highly diverse. This study focuses on SAgs because they are potent virulence factors that are highly diverse and therefore mirror of the variability of the species S. aureus. The goals of this work were (i) to identify virulence determinants by comparing the prevalence of SAg genes and phages among colonizing and invasive S. aureus isolates and to correlate it with the clonal background (ii) to determine the prevalence and the development of anti SAg antibodies in healthy S. aureus carriers and noncarriers as well as in bacteremia patients and (iii) to elucidate the reasons for the selective lack of neutralizing serum antibodies specific for a subgroup of SAgs the egc SAgs... Staphylococcus aureus Superantigen Genotypisierung Bakteriämie Kolonisierung Antikörper furunculosis enterotoxin gene cluster