Escherichia coli cellular responses to exposure to atmospheric‐pressure dielectric barrier discharge plasma‐treated N‐acetylcysteine solution

Mechanisms underlying the potent antimicrobial effects of plasma-activated seawater (PASW) on fish spoilage bacterium Shewanella putrefaciens

Plasma-activated seawater (PASW) presents a promising approach for marine fish preservation, yet its antimicrobial efficacy and mechanisms remain unclear. This study found that PASW exhibits superior bactericidal properties against the fish spoilage bacterium Shewanella putrefaciens compared to plasma-activated water (PAW), and increased effectiveness in preserving fish fillets. To clarify the mechanisms, a detailed investigation was conducted, including the generation of reactive oxygen/nitrogen species (ROS/RNS) and active halogen species in PASW, and their antimicrobial efficacy. Findings showed greater nitrite and hydrogen peroxide production in PASW relative to PAW, as well as the conversion of chloride/bromide ions into active species, which collectively enhanced PASW's antimicrobial activity. The synergistic action of ROS/RNS and active chlorine/bromine species in PASW promoted the generation of intracellular ROS, causing increased membrane damage, redox imbalance, and consequently higher bacterial mortality. This study enhances our understanding of PASW's antimicrobial effects and highlights its potential applications in the seafood industry.

Plasma-liquid interactions in the presence of organic matter-A perspective

As investigations in the biomedical applications of plasma advance, a demand for describing safe and efficacious delivery of plasma is emerging. It is quite clear that not all plasmas are "equal" for all applications. This Perspective discusses limitations of the existing parameters used to define plasma in context of the need for the "right plasma" at the "right dose" for each "disease system." The validity of results extrapolated from in vitro studies to preclinical and clinical applications is discussed. We make a case for studying the whole system as a single unit, in situ. Furthermore, we argue that while plasma-generated chemical species are the proposed key effectors in biological systems, the contribution of physical effectors (electric fields, surface charging, dielectric properties of target, changes in gap electric fields, etc.) must not be ignored.

Susceptibility and transcriptomic response to plasma-activated water of Listeria monocytogenes planktonic and sessile cells

Plasma-Activated Water (PAW) was generated from tap water using a surface dielectric barrier discharge at different discharge power (26 and 36 W) and activation time (5 and 30 min). The inactivation of a three-strain Listeria monocytogenes cocktail in planktonic and biofilm state was evaluated. PAW generated at 36 W-30 min showed the lowest pH and the highest hydrogen peroxide, nitrates, nitrites contents and effectiveness against cells on planktonic state, resulting in 4.6 log reductions after a 15-min treatment. Although the antimicrobial activity in biofilms formed on stainless steel and on polystyrene was lower, increasing the exposure time to 30 min allowed an inactivation >4.5 log cycles. The mechanisms of action of PAW were investigated using chemical solutions that mimic its physico-chemical characteristics and also RNA-seq analysis. The main transcriptomic changes affected carbon metabolism, virulence and general stress response genes, with several overexpressed genes belonging to the cobalamin-dependent gene cluster.

Irrigation of peritoneal cavity with cold atmospheric plasma treated solution effectively reduces microbial load in rat acute peritonitis model

Accurate and timely diagnosis of appendicitis in children can be challenging, which leads to delayed admittance or misdiagnosis that may cause perforation. Surgical management involves the elimination of the focus (appendectomy) and the reduction of the contamination with peritoneal irrigation to prevent sepsis. However, the validity of conventional irrigation methods is being debated, and novel methods are needed. In the present study, the use of cold plasma treated saline solution as an intraperitoneal irrigation solution for the management of acute peritonitis was investigated. Chemical and in vitro microbiological assessments of the plasma-treated solution were performed to determine the appropriate plasma treatment time to be used in in-vivo experiments. To induce acute peritonitis in rats, the cecal ligation and perforation (CLP) model was used. Sixty rats were divided into six groups, namely, sham operation, plasma irrigation, CLP, dry cleaning after CLP, saline irrigation after CLP, and plasma-treated saline irrigation after CLP group. The total antioxidant and oxidant status, oxidative stress index, microbiological, and pathological evaluations were performed. Findings indicated that plasma-treated saline contains reactive species, and irrigation with plasma-treated saline can effectively inactivate intraperitoneal contamination and prevent sepsis with no short-term local and/or systemic toxicity.

Evaluation of Cellular and Systemic Toxicity of Dielectric Barrier Discharge Plasma-Treated N-Acetylcysteine as Potential Antimicrobial Catheter Lock Solution

Intravenous catheter-related bloodstream infections are a cause of remarkable problems. Catheter lock solutions are used to keep catheter patency and prevent catheter-related bloodstream infections. The leakage of catheter lock solution to the bloodstream raises toxicity concerns. Plasma-treated liquids carry the potential to act as catheter lock solutions by virtue of their strong antimicrobial effects. The present study investigates the tolerance of the proposed solution in vitro and in vivo. N-acetylcysteine (NAC) solution was treated with atmospheric-air DBD plasma and antimicrobial assays were performed. The cytotoxicity of the plasma-treated NAC solution was evaluated on an EA.hy926 cell line. Intravenous administration of plasma-treated NAC solution in different doses was given to Sprague Dawley rats. One week after infusion with plasma-treated NAC solution, first, the blood samples were collected, and then liver, kidney, tail vein, heart, and lung tissue samples were collected from euthanized rats for histopathological examination. The cytotoxicity of plasma-treated NAC solution depended on plasma treatment time, contact time, and cell number. A strong antimicrobial effect with no cytotoxicity of plasma-treated NAC solution was observed in endothelial cells. Based on blood tests and histopathological examination, no signs of systemic toxicity were observed that can be correlated to the plasma-treated-NAC solution. This solution has the potential to be used as a catheter lock solution with strong antimicrobial properties, keeping catheter patency.