Using sophorolipids as an antiadhesive or release strategy to fight S. aureus catheter-related infection

Among medical devices, blood stream catheters are certainly included in the most used. Nevertheless, S. aureus catheter-related infection are of great concern and developing strategies to prevent bacteria colonization remain a big challenge.

This work aimed to modify medical grade silicon surfaces with sophorolipids, glycolipid biosurfactant, endowed with antimicrobial and antiadhesive properties. Two approaches were carried out: i) an antiadhesive strategy that uses the covalent bonding of sophorolipids to silicone surface and ii) a release-based strategy with the isolated most active sophorolipids adsorbed to the surface. Sophorolipids were produced by Starmerella bombicola, purified and isolated by automatic flash chromatography and identified using UHPLC-MS and RMN. Highest antimicrobial activity was observed with the isolated C18:0 and C18:1 diacetylated lactonic sophorolipids, that presented a minimum inhibitory concentration of 50 μg mL^-1. After functionalization, surfaces were evaluated by contact angle measurement, FTIR-ATR and AFM analysis. The antiadhesive strategy, using a mixture of acidic sophorolipids covalently bonded to the silicone surface, exhibited a biofilm reduction of 90% with no interference observed with HaCaT human cells. Concerning the release approach using the isolated C18:1 diacateylated lactonic sophorolipid, 5 log units reduction was observed on the biofilm formation and no reduction in HaCaT cells viability. Referring to the results above, sophorolipids seem promising biomolecules to prevent the occurrence of S. aureus catheter-related infections.