Enterococcus faecium is a ubiquitous bacterium that only recently emerged as a nosocomial pathogen. Infections mostly affect immunocompromised patients and multi-resistance of E. faecium often hampers treatment. This thesis focuses on determinants, which give pathogenic potential to E. faecium. In the first paper, two TirE proteins are described as novel virulence factors of E. faecium. The tirE ...