Effects of quorum sensing molecules of Pseudomonas aeruginosa GSU #3 on primary adhesion to hydrogel contact lenses

Acylated homoserine lactones (AHLs) are signal molecules that regulate population density-dependent gene expression (a phenomenon known as quorum sensing) in many Gram-negative bacteria. Production of several virulence factors is under quorum sensing control.; Effects of Pseudomonas aeruginosa AHLs and a synthetic furanone signaling antagonist on growth, elastase production, and primary adhesion of P. aeruginosa GSU #3 (a microbial keratitis isolate) and quorum sensing (QS) mutants to hydrogel contact lenses were evaluated. Relative primary adhesion capacities of P. aeruginosa and S. epidermidis to a hydrogel lens in pure and mixed culture also were examined.; Primary adhesion by P. aeruginosa to a hydrogel lens was more dense and rapid than that of S. epidermidis. When lenses were challenged with S. epidermidis first, primary adhesion of P. aeruginosa was significantly diminished. These data support the notion that normal biota may be protective for the eye. Studies of exposure of multiple lenses to a standard P. aeruginosa inoculum suggest that a limited number of cells (selected phenotype) are involved in primary adhesion.; AHLs had no observed effects on growth or primary adhesion of the tested strains, but the furanone increased the growth of a lasI- rhlI-QS mutant and was toxic to selected staphylococci. Primary adhesion of P. aeruginosa GSU #3 was somewhat decreased with silicone hydrogel lenses soaked in 100ug/mL furanone. This effect appeared to be strain and material specific and possibly due to a chemical interaction of the furanone system with the substratum.; Exogenous AHLs had no effect on elastase production of wild type strains, but restored elastase production in QS mutants. The furanone decreased elastase production by roughly 50% in wild type strains, but increased elastase production of QS mutants by more than 70%. As the furanone was also biocidal for staphylococci found in the normal eye, these observations are of note if furanones are considered candidates for antimicrobial additives for contact lenses or other devices.