Role of Stenotrophomonas Maltophilia Pili Iin Biofilm And Virulence

Abstract

Stenotrophomonas maltophilia is an emerging multidrug-resistant, Gram-negative opportunistic pathogen. It causes many hospital-acquired infections such as sepsis, endocarditis, meningitis, and catheter-related urinary tract infections. It also affects individuals with cystic fibrosis, exacerbating their lung condition. S. maltophilia often causes pathogenesis through the formation of biofilms. However, the molecular mechanisms S. maltophilia uses to carry out these pathogenic steps are unclear. The SMF-1 chaperone/usher pilus has been thought to mediate S. maltophilia attachment. To confirm this role, we created an isogenic deletion of the smf-1 pilin gene and observed a defect in biofilm compared to wild type. We also discovered 2 additional chaperone/usher pilus operons, mutation of which also caused attenuation in biofilm levels. Analysis of S. maltophilia clinical strains and S. maltophilia complete genomes listed in NCBI showed that these three pili are prevalent and highly conserved, suggesting a vital role in infection. Intriguingly, through TEM studies, we found that the mutation of one pilus is not phenotypically compensated by another. Infection of Galleria mellonella larvae revealed increased virulence of the pilus mutants. Additionally, we also demonstrated a relationship between pilus and flagella contributing to the overall biofilm development of S. maltophilia. Understanding their activity may help identify therapeutic targets for this pathogen.