Physical and Microbiological Characterisation of Staphylococcus epidermidis Inactivation by Dielectric Barrier Discharge Plasma

Abstract

The inactivation of the Gram‐positive bacteria Staphylococcus epidermidis (ATCC 12228) in its vegetative state was studied in vitro after exposure to cold atmospheric pressure plasma generated by direct dielectric barrier discharge (DBD). Compared to UV radiation at 254 nm, plasma UV emission yielded no significant contribution to bacterial inactivation. Analysis of bacterial growth inhibition revealed a pH dependency on growth media. Yet, measurements combined with numerical simulations excluded the pH shift induced by plasma generated reactive species as the main cause of bacterial inactivation. Scanning electron microscopy (SEM) images showed no alteration of cell walls, while fluorescence microscopy revealed lethal damage to cell membranes even after 1 s treatment. When the cell membrane was already severely damaged, also degradation of the bacterial DNA by plasma treatment was found. We conclude that membrane damage due to reactive oxygen species (ROS) and DNA degradation are the main mechanisms of plasma‐induced bacterial death that is aggregated by milieu acidification.

Inactivation of Microorganisms Using Cold Atmospheric Pressure Plasma with Different Temporal Discharge Characteristics

“…The gram‐negative bacteria E. coli and P. aeruginosa and the yeast C. albicans showed a different pattern of damage after the plasma treatment than the gram‐positive bacteria S. epidermidis does. The latter did not show any morphological change after the plasma treatment . On the one hand, a reason might be that the cell wall consisting of peptidoglycans is much stronger and, thus, can be more than ten times thicker than a gram‐negative cell wall.…”

“…The antiseptic efficacy of direct plasma generated by a dielectric barrier discharge (DBD) on gram‐positive Staphylococcus epidermidis has already been studied and was published in a previous paper . To broaden the database of the microorganisms investigated, the antiseptic efficacy on gram‐negative bacteria ( Escherichia coli and Pseudomonas aeruginosa ) and on yeast ( Candida albicans ) was studied.…”

Evaluation of Cold Plasma Treatment and Safety in Disinfecting 3-week Root Canal Enterococcus faecalis Biofilm In Vitro

“…Plasma induced UV intensities and thermal impact on the bacteria can be neglected. Thus, the major cause of cell death in this study is due to the membrane damage induced by cold plasma treatment (34). The results of OES indicated that the reactive oxygen species, especially oxygen, was generated and led to oxidative stress and cell damage, which are the key inactivation agents in cold plasma (35).…”

Cold atmospheric pressure plasmas in dermatology: Sources, reactive agents, and therapeutic effects

“…The synergistic effect of the plasma treatment, such as sterilization, increase in microcirculation, and skin acidification provides the advantage of using plasma over, for example, pulse electric field or phototherapy. [ 91–96 ] Further research focused on understanding the effect of plasma at either the level of individual molecules or at the cellular level. For example, plasma can induce a biologically relevant modification in proteins, [ 97 ] DNA, [ 98 ] and amino acids.…”