Eradication of methicillin-resistantStaphylococcus aureusbiofilms by surface discharge plasmas with various working gases

Abstract

Surface discharge plasmas have advantages in various applications, such as the treatment of wound infections. However, the effects of surface discharge plasmas on biofilms have not been studied. In this study, the inactivation of methicillin-resistant Staphylococcus aureus biofilms by surface discharge plasmas with four working gases, namely, He + 1% air, Ar + 1% air, synthetic air, and natural air, was investigated to elucidate the correlation between the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) and the biofilm eradication performance. The experimental results demonstrated that the surface plasma with Ar + 1% air produced the highest concentrations of excited reactive species in gas phase and of NO − 2 and O •− 2 / . NO 2 /ONOO − in the liquid phase, while the surface plasma with synthetic air produced largest amount of NO − 3 and 1 O 2 in the liquid phase. For methicillin-resistant S. aureus biofilms, the inactivation effects of the surface plasmas with Ar + 1% air and natural air were similar and more pronounced compared with the other gases, while the inactivation effect of surface plasma with He + 1% air was the least pronounced. The biofilm inactivation and ROS penetration by He + 1% air plasma could be enhanced by a low concentration of nitrite and nitrate. Based on the results, it was proposed that plasmagenerated long-lived species promoted the penetration of reactive species in biofilms, and the penetrated ROS and RNS jointly contributed to the inactivation of methicillin-resistant S. aureus biofilms.

Cold Atmospheric-Pressure Plasma Caused Protein Damage in Methicillin-Resistant Staphylococcus aureus Cells in Biofilms

“…The CAP device was similar to the previous study [ 45 ]. The surface discharge structure of the CAP consisted of a high-voltage plane electrode, a liquid-facing grounded mesh electrode with a hexagonal shape, and a dielectric layer (made of polytetrafluoroethylene) sandwiched between the two electrodes ( Figure 1 ).…”

“…The culture of S. aureus biofilms was performed as previously described [ 45 ]. S. aureus ATCC33591, a methicillin-resistant strain, was purchased from the American Type Culture Collection (ATCC).…”

Plasma-Activated Saline Promotes Antibiotic Treatment of Systemic Methicillin-Resistant Staphylococcus aureus Infection

“…Staphylococcus aureus ATCC33591, a methicillin-resistant strain, was purchased from the American Type Culture Collection (ATCC, Maryland, USA). The culture of biofilms was performed as described previously [ 67 ]. After culturing for three days, the medium was carefully removed, and the silica films with biofilms were gently washed three times with saline solution (0.9% NaCl).…”

Low-Temperature Gas Plasma Combined with Antibiotics for the Reduction of Methicillin-Resistant Staphylococcus aureus Biofilm Both In Vitro and In Vivo

“…The biofilms were cultured as described previously [ 9 , 29 ]. S. aureus ATCC33591, a methicillin-resistant strain, was purchased from the American Type Culture Collection (ATCC).…”

“…The LTGP device was similar to that used in previous studies [ 9 , 29 ]. As shown in Figure 1 , the surface discharge structure of the LTGP consisted of a high-voltage plane electrode, a liquid-facing grounded mesh electrode with a hexagonal shape, and a dielectric layer (made of polytetrafluoroethylene) sandwiched between the two electrodes.…”