Investigation of bacteriostatic effect of iontophoresis in Gram positives and Gram negatives bacterias

Abstract

Healing is the process of biologic tissue reparation, coordinated by a series of cellular and molecular events. A strategy that has been under study to accelerate the healing process is electric stimulation and that can be done by iontophoresis. Iontophoresis is a method for topical administration of drugs, in a none invasive way, that consists on the application of electric current in low intensity, in order to facilitate the penetration through the stratum corneum. There are evidences that electric stimulation is capable of promoting the migration of defense cells, involved in the healing process, collagen deposits and angiogenesis. In addition to that advantages, iontophoresis can inhibit bacteria growth, which can benefit the healing process since the growth of microorganisms in the wound site can delay the healing. Preliminary studies held in our laboratory have shown that the application of electric current of 0,2 mA/cm2 from an positive electrode (anodic) in Gram positive bacteria culture in solid media was capable to prevent their growth. Nevertheless, the same current wasn't able to have that bacteriostatic effect in Gram negative bacteria. Some hypothesis have been created in literature to explain the bacteriostatic effect of electric current, however, the mechanisms involved still haven't been discovered. Therefore, the objective of this project is to evaluate the bacteriostatic action of iontophoresis in Gram positive and Gram negative bacterias, as well as the mechanisms involved, using the strains Staphylococcus aureus (ATCC 6538), Staphylococcus epidermidis (ATCC 12228), Escherichia coli (ATCC 25922) e Pseudomonas aeruginosa (ATCC 15442).The influence of the electric current on the bacterial growth will be evaluated from the application of an electric current of 0,4 mA with different electric circuit schemes, in which the positive electrode can be in direct or indirect contact with the culture. The circuit that shows most promising, related to the bacteriostatic effect, is going to be used to evaluate the effect of different electric current duration and intensity. In order to investigate the mechanisms involved in the bacteria growth inhibition the production of hydrogen peroxide will be assessed after the passage of the electric current, by means of Merckoquant strips. Moreover, to verify if the iontophoresis effect is linked with alterations in the cellular permeability, different concentrations of arginine will be added in the bacteria culture. Furthermore, before and after electric stimulation, the zeta potential and osmolarity of the microorganisms are going to be evaluated.