Mechanical deformation of elastomer medical devices can enable microbial surface colonization

Abstract

Elastomers such as silicone are common in medical devices (catheters, prosthetic implants, endoscopes), but they remain prone to microbial colonization and biofilm infections. For the first time, our work shows that rates of microbial surface attachment to polydimethylsiloxane (PDMS) silicone can be significantly affected by mechanical deformation. For a section of bent commercial catheter tubing, bacteria (P. aeruginosa) show a strong preference for the ‘convex’ side compared to the ‘concave’ side, by a factor of 4.2. Further testing of cast PDMS materials in bending only showed a significant difference for samples that were manually wiped (damaged) beforehand (1.75 × 104 and 6.02 × 103 cells/mm2 on the convex and concave sides, respectively). We demonstrate that surface microcracks in elastomers are opened under tensile stress (convex bending) to become ‘activated’ as sites for microbial colonization. This work demonstrates that the high elastic limit of elastomers enables these microcracks to reversibly open and close, as ‘dynamic defects’. Commercial catheters have relatively high surface roughness inherent to manufacturing, but we show that even manual wiping of newly-cast PDMS is sufficient to generate surface microcracks. We consider the implication for medical devices that feature sustained, surgical, or cyclic deformation, in which localized tensile conditions may expose these surface defects to opportunistic microbes. As a result, our work showcases serious potential problems in the widespread usage and development of elastomers in medical devices.

Wettability and Bactericidal Properties of Bioinspired ZnO Nanopillar Surfaces

“…As such, PDMS coatings can become contaminated and retain bacteria that are able to multiply and form biofilms in the absence of appropriate cleaning and sterilization protocols. 30 By contrast, metal-oxide photocatalysts, such as TiO 2 and ZnO, have demonstrated antimicrobial properties, which are attributed to the reactive free radicals generated under illumination. 31−36 Specifically, their photocatalytic activities can either lead to cell membrane disorganization or induce oxidative stress in bacterial cells.…”

“…This means that PDMS does not interact with or directly affect microorganisms, and therefore, it does not have inherent antimicrobial properties of its own. As such, PDMS coatings can become contaminated and retain bacteria that are able to multiply and form biofilms in the absence of appropriate cleaning and sterilization protocols …”

“…As such, PDMS coatings can become contaminated and retain bacteria that are able to multiply and form biofilms in the absence of appropriate cleaning and sterilization protocols. 30 …”