Type VI-secretion system-mediated competition and virulence in clinical and environmental Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is an emerging opportunistic pathogen associated with severe nosocomial infections with limited treatment options due to resistance to multiple antibiotics. Mechanisms of pathogenicity and fitness are relatively poorly understood in the species, which is ubiquitous in the environment and shows high genome plasticity. Type VI secretion systems (T6SS) are molecular machines that inject effector proteins into target cells, playing fundamental roles in bacterial interactions within polymicrobial communities and hosts. In this study, we identify and characterize T6SSs in a diverse set of clinical and environmental isolates of S. maltophilia from Brazil, revealing their role in bacterial antagonism and virulence. This study provides new insights into the mechanisms that contribute to S. maltophilia's ability to thrive in distinct environments, also contributing to the understanding of the complex genomic variability within the species.