Molecular characterization of virulence patterns in Pseudomonas aeruginosa strains isolated from respiratory and wound samples

The versatile human opportunistic pathogen, Pseudomonas aeruginosa is responsible for a large spectrum of infections due to its impressive array of virulence factors, whose coordinated expression is regulated by many virulence regulatory systems. Among them an important role is playing by two well interrelated (las and rhl) quorum-sensing (QS) systems. The mutations occurred in either of the QS genes are associated with low virulence and a poor infective potential. The purpose of this study was to perform the molecular characterization of QS systems and of eleven extracellular virulence factors, whose expression is regulated by QS systems, in 49 P. aeruginosa strains isolated from respiratory tract secretions and wound secretions samples from patients with cardiovascular surgery associated infections in order to establish the correlations between certain virulence patterns and the clinical origin of bacterial strains. The results of this study showed that all analyzed strains possess QS genes, and five of eleven virulence genes regulated by QS systems. The protease IV and ExoU genes were specifically associated with the origin of the clinical strains, proving that these virulence genes could represent useful diagnosis markers for differentiating clinical P. aeruginosa strains.