Touch transfer of microorganisms on polymer surfaces†

Abstract

The transfer of bacteria between dry, high-touch surfaces in healthcare settings is a key contributor to hospital-acquired infections (HAIs). In this study, we systematically investigated the relationship between the chemistry of polymer surfaces and the corresponding touch-transfer of microorganisms. The polymers investigated included polymer zwitterions, PEGylated polymers, poly(tetrafluoroethylene) (PTFE), and polystyrene (PS). Water contact angle measurements confirmed the breadth of surface energies of these polymers, ranging from <25° (polymer zwitterion) to >100° (PTFE). A touch transfer model was developed to study bacteria transfer by “finger touches” on an agar plate. The amount of Escherichia coli (E. coli) or Staphylococcus aureus (S. aureus) transferred after each touch was quantified via plate counting. For E. coli, the transfer rate was ∼29% on zwitterionic copolymer surfaces, whereas PS exhibited a much higher rate of ∼67%. For S. aureus, the transfer rate was ∼17% for the polymer zwitterion and ∼100% for PS. The low transfer rates from the polymer zwitterion were comparable to those of PTFE (∼19% for E. coli and ∼17% for S. aureus). These findings demonstrate the role of polymer composition and surface chemistry in bacterial transfer and provide insights for designing materials that effectively minimize microbial transmission in healthcare environments.