Stenotrophomonas maltophilia is a bacterium that is often associated with hospital acquired infections. It adheres to medical devices such as ventilator systems or surgical instruments. Infection of immunocompromised patients or patients with cystic fibrosis with this bacterium is associated with increased mortality. Treatment of S. maltophilia infection is hampered by its high degree of resistance against many commonly used antibiotics. This bacterium is able to communicate by signaling through special fatty acids, the so-called diffusible signaling factors (DSF), and by releasing outer membrane vesicles (OMVs). This project is aiming to investigate the molecular principles of communication between Stenotrophomonas maltophilia and other pathogens via these two signaling pathways. Therefore, we will perform a detailed analysis of the protein and nucleic acids content of these OMVs. Furthermore, we will analyse the cellular response on DSF and OMV signaling and determine the role of these signals in the development and spread of resistance and virulence in S. maltophilia and in co-infecting species like Pseudomonas aeruginosa and Burkholderia cenocepacia.