VIRULENCE FACTORS OF PSEUDOMONAS AERUGINOSA STRAINS ISOLATED FROM CLINICAL SAMPLES AND ROLE OF QUORUM SENSING SIGNAL MOLECULES IN THE PATHOGENESIS OF THE DISEASE

Introduction: Pathogenicity of Pseudomonas aeruginosa depends on multiple cell-associated factors and virulence factors including "Quorum sensing (QS)" molecules. QS system enables the bacterium to determine the population density around it and the bacterium uses this data to control the regulation of many of its genes. The aim of this study was to determine whether there was QS insufficient subspecies infective for humans, and to identify the relations between specific infection types and virulence factors. Materials and methods: A hundred P. aeruginosa strains isolated from different clinical specimens were used in our study. Quantitative measurements of elastase, alkaline protease, pyocyanin, and biofilm formation were done. Strains were investigated to produce long and short chain signal molecules taken part in QS system. Results: Elastase activities of the subspecies isolated from sputum and blood specimens were detected higher than those from other localizations. Pyocyanin values of the urine specimens were detected higher than those of blood, wound and sputum isolates. Biofilm formation level of the urinary isolates was significantly higher than the other isolates. All the subspecies produced long chain signal molecule, whereas 29 isolates produced short chain signal molecule. Productions of elastase, alkaline protease and pyocyanin in the short chain signal molecule producing strains were higher than those cannot produce. Conclusion: These results suggested that the Quorum sensing could make the strains much virulent, and could play an impor- tant role in pathogenicity. To date, the QS system has not been clearly identified yet for many microorganisms, however, the agents targeting the QS system may be therapeutic alternatives in the treatment and prophylaxis of infections in the future.