Screening & profiling of quorum sensing signal molecules in Pseudomonas aeruginosa isolates from catheterized urinary tract infection patients

BACKGROUND & OBJECTIVES Catheter associated urinary tract infections are the second most common nosocomial infections and Pseudomonas aeruginosa is the third most common organism responsible for these infections. In this study P. aeruginosa isolates from catheterized urinary tract infection patients were screened and profiled for the presence of different type of quorum sensing (QS) signal molecules. METHODS Screening and quantitation of AHLs was done by using cross feeding assay and by determining β-galactosidase activity respectively using Escherichia coli MG4 as reporter strain. Further, AHL profiles were determined by separating AHLs on TLC coupled with their detection using Chromobacterium violaceum CV026 and Agrobacterium tumifaciens A136 biosensor strains. RESULTS All uroisolates from catheterized patients having urinary tract infections were found to be producers of QS signal molecules. There were differences in amounts and type of AHL produced amongst uroisolates of P. aeruginosa. Several AHLs belonging to C4-HSL, C6-HSL, oxo-C6-HSL, C8-HSL, C10-HSL and C12-HSL were determined in these strains. INTERPRETATION & CONCLUSIONS Simultaneous use of more than one reporter strain and assay method proved useful in determining the AHLs profile in uroisolates of P. aeruginosa. Observed differences in the amounts and types of AHLs may reflect differences in virulence potential of P. aeruginosa to cause UTIs which can be further confirmed by employing animal model system. The present study speculates that production of QS signal molecules may act as a new virulence marker of P. aeruginosa responsible for causing catheter associated UTIs and can be considered as futuristic potential drug targets towards treatment of UTIs.