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M. E. Zegans, C. T. Bramante, C. M. Toutain; Inhibition of Pseudomonas Aeruginosa Biofilm Formation by Polysorbate 80, a Common Additive to Eye Drops. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5986.
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Bacterial biofilms are associated with pathogenic infections and antibiotic resistance. The gram negative bacterium Pseudomonas aeruginosa (Pa) is able to form biofilms on a variety of medical implants, including contact lenses. Polysorbate 80 (PS80) is a non ionic detergent found in many medications including eye drops. In this report we describe the effect of PS80 on biofilm formation by Pa.
All genetic, biochemical and microbiologic assays were performed following previously published protocols. Biofilm assays were performed on different abiotic surfaces. Bacteria were incubated in M63 supplemented with glucose and casamino acids for 24 hours at 37°C. The medium was supplemented with PS80 at concentrations ranging from 0.1% to 0.001%.
The lab strain, PA14, is not able to form biofilms on PVC, glass or contact lenses in presence of PS80. We obtained similar results with the lab strain PAK as well as half of 99 clinical isolates of Pa tested. The ophthalmic NSAID Xibrom TM containing 0.15% PS80 is also able to inhibit biofilm formation of PA14 and PAK. We identified a transposon mutant of PA14 able to form biofilms in presence of PS80. Investigation of this mutant revealed increased expression of lipA, a gene which codes for a secreted lipase. As expected, we observed increased lipase/esterase activity in this mutant compared to wild type PA14 in a biochemical assay
We demonstrate that PS80 inhibits Pa biofilm formation under a variety of conditions and at concentrations lower than those present in commercial eye drops. The resistance of the transposon mutant and other strains to this effect suggests that it is a genetically controlled process. Previous work has shown that Pa lipases can cleave PS80 at its ester bond. Our data suggest that LipA cleavage of PS80 eliminates its antibiofilm effect. These novel observations suggest that PS80, a compound considered inactive by the pharmaceutical industry and well tolerated on the ocular surface, can exert a significant effect on a bacterial group behavior
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