Electroporation of biofilms

Abstract

The extraordinary resistance of bacterial biofilms against the antimicrobials and human immune system raises a grave issue in the medical field. This resistance is due to the confinement of bacteria into a highly dense extracellular matrix. This matrix serves as a filter and increases the concentration needed to kill bacteria from 100 to 1000 times, in comparison with free-floated bacteria (planktonic). Within context, the development of new therapeutic strategies is required. To achieve this aim, the pulsed electric fields (PEFs) are a promising technology. The purpose of this chapter is to introduce the complexity of the biofilms and the phenomenon involved in their formation, maturation, and proliferation. The mechanisms of adhesion and the roles of extracellular matrix are specifically discussed. Then, the chapter considers two different strategies which use the PEF technology to inactivate the biofilms. The first approach is direct disinfection of biofilms by PEF. In this case, strong electric fields are applied during a short time. The aim is to induce a bacterial inactivation by irreversible damages of the cell envelope by the production of reactive oxygen species. This method is efficient to prevent in vivo, the biofilm formation on burned wound. The second strategy is to expose biofilm with low electric fields during a long period and in combination with antimicrobials. This technique is called the bioelectric effect and allows removing of the antibiotic resistance of biofilms. The mechanism is not fully understood, but the observed effect is probably due to mass transfer electrophoresis and disruption of the extracellular matrix.