Viscoelasticity of biofilms and their recalcitrance to mechanical and chemical challenges

Abstract

We summarize different studies describing mechanisms through which bacteria in a biofilm mode of growth resist mechanical and chemical challenges. Acknowledging previous microscopic work describing voids and channels in biofilms that govern a biofilms response to such challenges, we advocate a more quantitative approach that builds on the relation between structure and composition of materials with their viscoelastic properties. Biofilms possess features of both viscoelastic solids and liquids, like skin or blood, and stress relaxation of biofilms has been found to be a corollary of their structure and composition, including the EPS matrix and bacterial interactions. Review of the literature on viscoelastic properties of biofilms in ancient and modern environments as well as of infectious biofilms reveals that the viscoelastic properties of a biofilm relate with antimicrobial penetration in a biofilm. In addition, also the removal of biofilm from surfaces appears governed by the viscoelasticity of a biofilm. Herewith, it is established that the viscoelasticity of biofilms, as a corollary of structure and composition, performs a role in their protection against mechanical and chemical challenges. Pathways are discussed to make biofilms more susceptible to antimicrobials by intervening with their viscoelasticity, as a quantifiable expression of their structure and composition.

Synergy of brushing mode and antibacterial use on in vivo biofilm formation

“…25 Since biofilms have visco-elastic properties, biofilm will first expand due to energy input during powered brushing after which it will detach. [26][27][28] However, biofilm left-behind will remain in its expanded, more open state enabling better antibacterial penetration, which explains why in the current study we observe a greater reduction in biofilm viability upon application of antibacterial regimens when using a powered brush versus a manual brush. Note that the use of either one of the brushing methods without the use of an oral antibacterial regimen hardly affected the viability of the biofilm compared to an unbrushed biofilm.…”

Critical review on biofilm methods

“…In fact, viscoelastic properties of biofilms influence antimicrobial penetration and removal of biofilm from surfaces and therefore performs a role in their protection against mechanical and chemical challenges (Peterson et al, 2015). On a macroscopic scale, viscoelasticity can be measured by quantifying the compression of the biofilm under a low load (Korstgens et al, 2001).…”

Implicancias Estructurales y Fisiológicas de la Célula Bacteriana en los Mecanismos de Resistencia Antibiótica

“…Se ha demostrado que las biopelículas tienen una alta persistencia una vez que se establecen las infecciones y por lo tanto son responsable de muchos procesos infecciosos crónicos (Peyyala & Ebersole, 2013). La baja capacidad de penetración de los antimicrobianos en la biopelícula es el principal obstáculo para el tratamiento antibiótico de las infecciones, generando un fenotipo con capacidad de resistencia a altas concentraciones de antimicrobianos y modulación de los mecanismos de defensa del hospedador, incluso cuando son totalmente susceptibles a tales agentes en condiciones planctónicas (Peterson et al, 2015). Este mecanismo de resistencia se ha denominado "biofilm bacteriano recalcitrante a antibióticos", el cual es un proceso reversible y no heredado, y desaparece cuando se interrumpe la biopelícula y las bacterias vuelven a un estado planctónico (Lebeaux et al).…”