Bacterial interactions with surfaces are at the heart of many infection-related problems in healthcare. In this work, the interactions of clinically relevant bacteria with immobilized liquid (IL) layers on oil-infused polymers are investigated. Although oil-infused polymers reduce bacterial adhesion in all cases, complex interactions of the bacteria and liquid layer under orbital flow conditions are uncovered. The number of adherent Escherichia coli cells over multiple removal cycles increases in flow compared to static growth conditions, likely due to a disruption of the liquid layer continuity. Surprisingly, however, biofilm formation appears to remain low regardless of growth conditions. No incorporation of the bacteria into the layer is observed. Bacterial type is also found to affect the number of adherent cells, with more E. coli remaining attached under dynamic orbital flow than Staphylococcus aureus, Pseudomonas aeruginosa under identical conditions. Tests with mutant E. coli lacking flagella confirm that flagella play an important role in adhesion to these surfaces. The results presented here shed new light on the interaction of bacteria with IL layers, highlighting the fundamental differences between oil-infused and traditional solid interfaces, as well as providing important information for their eventual translation into materials that reduce bacterial adhesion in medical applications.
Y.K. and I.S. contributed equally to this work. The authors thank Ronn Friedlander for providing the E. coli Δ iC mutant, Phil Kim for helpful advice, and Abigail Weigang for editing assistance. J.V.I.T. thanks the European Commission for support through the Seventh Framework Programme (FP7) Project DynaSLIPS 626954. This material was based upon work supported by the Defense Advanced Research Projects Agency Grant N66001-11-1-4180 and Contract HR0011-13-C-0025.