Efficacy Of Cold Atmospheric Plasma Research Articles

Therapeutic efficacy of cold atmospheric plasma in four golden retrievers with acute otitis externa.

Cold atmospheric plasma (CAP) is a new therapeutic tool used to treat various skin diseases in humans and animals. To evaluate the effect of CAP in the treatment of canine acute otitis externa (AOE). Four client-owned golden retriever dogs with bilateral AOE. After cleaning with a commercial ear cleanser, right ears (STANDARD group) were treated with an antibiotic/antifungal/corticosteroid combination and left ears (CAP group) were treated with CAP every three days for a total of four treatments. Cytological score and otitis index score (OTIS)3 were recorded for each ear on Day (D)0, D10 and D15. At D10 and D15, owners and investigators recorded an overall assessment. In both groups, OTIS3 and cytological score decreased over the study period. The overall assessment scale ranged from moderate to excellent in both groups. Cold atmospheric plasma treatment showed equal therapeutic effect compared with a commercial topical anti-inflammatory and antimicrobial ear treatment.

Influence of Biofilm Maturity on the Antibacterial Efficacy of Cold Atmospheric Plasma in Oral Microcosm Biofilms.

As biofilms mature, biomass and extracellular polysaccharide (EPS) content increases, enhancing pathogenicity. Therefore, this study aimed to evaluate the antibacterial efficacy of cold atmospheric plasma (CAP) against oral microcosm biofilms and the influence of biofilm maturity on treatment. Oral microcosm biofilms were cultured on hydroxyapatite disks for 2 and 6 days. Based on the treatment and biofilm maturity, these were subsequently allocated into six groups (N = 19 each): Groups 1 and 2 were incubated with distilled water for 1 min; Groups 3 and 4 were treated with CAP for 2 min, and Groups 5 and 6 were treated with 0.12% chlorhexidine gluconate for 1 min. Groups 1, 3, and 5 represent 2-day biofilms, and Groups 2, 4, and 6 represent 6-day biofilms. Treatments were repeated daily for 5 days. Antibacterial efficacy was analyzed by measuring oral biofilms' red fluorescence intensity (RatioR/G) and quantifying EPS content and bacterial viability. The RatioR/G was 1.089-fold and 1.104-fold higher in Groups 4 and 6 than in Groups 3 and 5 following antibacterial treatment, respectively (p < 0.001). EPS content increased by 1.71-fold in Group 6 than in Group 5 (p < 0.001). Bacterial survival rate was the lowest in Group 3 (p = 0.005). These findings underscore the relevance of CAP treatment in maintaining antibacterial efficacy regardless of the biofilm development stage, highlighting its potential utility in oral care.

Emerging Alternaria toxins present in naturally contaminated dried tomatoes and their reduction using cold atmospheric plasma

This study investigated the efficacy of cold atmospheric plasma (CAP) treatment in degrading the emerging Alternaria toxins as pure molecules and as natural contaminants in dried tomatoes. The analyses of 25 batches of dried tomatoes showed that more than 40% of samples were contaminated with tenuazonic acid (TeA), one with Alternariol (AOH), while Tentoxin (TEN), Alternariol monomethyl ether (AME) and Altenuene (ALT) were not detected. CAP under ozone (O3) and NOx regimes were used to reduce the mycotoxin contamination, the results shown that O3 regime was more effective against all mycotoxins tested, while NOx regime showed different efficacy depending on the specific mycotoxin. The Weibull model proved to be appropriate for the degradation kinetics of all Alternaria toxins, regardless of the kinetic order they possess. Under the O3 regime, the resistance of the mycotoxin was AME > AOH > TEN > TeA > ALT. Our studies have shown for the first time that CAP reduces Alternaria toxins in naturally contaminated dried tomatoes. In particular, the rate of degradation under O3 regime increased significantly with the longest exposure time, reaching 52.80 ± 1.21 % of mycotoxin degradation. Our results expand our knowledge of CAP treatment as a potential means of reducing mycotoxin contamination in food. Further studies will be carried out to investigate the potential mycotoxin degradation products and to ensure food safety.

A Two-Stage Transferred Cold Atmospheric Plasma as a Unique Therapeutic Strategy for Targeting Colon Cancer Stem Cells.

The study examines the induction of apoptosis in colon cancer stem cells (CCSCs) within a 3D culture setting, employing an innovative cold atmospheric plasma (CAP) transmission method known as two-stage transferred cold atmospheric plasma (TS-TCAP). TS-TCAP is a partially or fully ionized non-thermal gaseous mixture that comprises photons, charged and neutral particles, and free radicals, which has gained traction in biomedical applications such as cancer therapy. TS-TCAP impacts CCSCs via a continuous, two-step transport process, facilitating the efficient delivery of reactive oxygen and nitrogen species (RONS). The key cellular factors of CCSCs impacted by TS-TCAP treatment, encompassing the secretion and expression levels of IL-6 and IL-8, apoptotic cell count, and expression of BAX, BCL-2, and KI-67 proteins, were evaluated using qrt-ELISA, Annexin V, and qrt-PCR procedures, respectively. The outcomes of CCSCs treatment with TS-TCAP reveal a notable rise in the number of apoptotic cells (P<0.0001), diminished secretion, and gene expression of IL-6 and IL-8 (P<0.0001), accompanied by favorable alterations in BCL-2 and BAX gene expression (P<0.0001). Additionally, a notable decrease in KI-67 expression was observed, correlating with a reduction in CCSCs proliferation (P<0.0001). As well, this study underscores the anti-cancer potential of TS-TCAP, showcasing its efficacy in reducing CCSCs survival rates. However, further pre-clinical and clinical trials are necessary to evaluate CAP's efficacy, safety, and potential synergistic effects with other therapies thoroughly. Overall, TS-TCAP presents a promising alternative for CCSCs treatment, pending further investigation and refinement.

Efficacy of Cold Atmospheric Plasma vs. Chemotherapy in Triple-Negative Breast Cancer: A Systematic Review.

Breast cancer is a growing disease, with a high worldwide incidence and mortality rate among women. Among the various types, the treatment of triple-negative breast cancer (TNBC) remains a challenge. Considering the recent advances in cold atmospheric plasma (CAP) cancer research, our goal was to evaluate efficacy data from studies based on chemotherapy and CAP in TNBC cell lines and animal models. A search of the literature was carried out in the PubMed, Web of Science, Cochrane Library, and Embase databases. Of the 10,999 studies, there were fifty-four in vitro studies, three in vivo studies, and two in vitro and in vivo studies included. MDA-MB-231 cells were the most used. MTT, MTS, SRB, annexin-V/propidium iodide, trypan blue, and clonogenic assay were performed to assess efficacy in vitro, increasing the reliability and comprehensiveness of the data. There was found to be a decrease in cell proliferation after both chemotherapy and CAP; however, different protocol settings, including an extensive range of drug doses and CAP exposure times, were reported. For both therapies, a considerable reduction in tumor volume was observed in vivo compared with that of the untreated group. The treatment of TNBC cell lines with CAP proved successful, with apoptosis emerging as the predominant type of cellular death. This systematic review presents a comprehensive overview of the treatment landscape in chemotherapy and CAP regarding their efficacy in TNBC cell lines.

Efficacy of Cold Atmospheric Plasma on Pathogenicity of Oral Microcosm Biofilms

This study aimed to compare the longitudinal efficacy between chlorhexidine gluconate (CHX; 0.12%) and cold atmospheric plasma (CAP) in reducing oral biofilm pathogenicity, utilizing a quantitative light-induced fluorescence-digital (QLF-D) camera. Oral microcosm biofilms were developed for 2 days on 57 hydroxyapatite disks. These biofilms were treated with distilled water for 1 min, CHX for 1 min, and CAP for 2 min over the course of 6 days. The red fluorescence intensities of the biofilms were measured using a QLF-D and expressed as pre- and post-treatment red/green ratios (RatioR/G). The bacterial viability (ratio of the green-stained area to the total stained area, RatioG/G+R) was calculated using live/dead bacterial staining; the total and aciduric bacterial counts were determined. A significant intergroup difference was found between RatioR/G changes according to the treatment period (p &lt; 0.001). The RatioR/G observed within the CAP-treated group was significantly lower compared with the CHX-treated group at every interval of measurement (p &lt; 0.001). The CAP-treated group also exhibited a lower RatioG/G+R and more weakened bacterial aggregation compared with the CHX-treated group (p &lt; 0.05). In the group treated with CAP, the counts of both total and aciduric bacteria were substantially reduced compared with the DW group, with a statistically significant reduction (p &lt; 0.001). Therefore, CAP may be more effective in minimizing oral microcosm biofilm pathogenicity than 0.12% CHX.

Sterilization effect and mechanism exploration of a mode‐combination method on Staphylococcus aureus in thick ice layers in a large sealed freezer

AbstractCold‐chain transport is a crucial cross‐regional transmission pathway for severe acute respiratory syndrome coronavirus 2 and other microorganisms. In this study, the mode‐combination method is adopted for sterilization in a 1.138 m3 freezer by mixing effluent gases of NOx and O3 mode air discharges. The mixed gas can effectively inactivate Staphylococcus aureus in 10 mm ice within 3 h, which significantly surpasses O3 gas. Moreover, the inactivation effect of the mixed gas can penetrate deep into ice, contrasting with the surface effect of O3 gas. This disparity is linked to the difference in penetration depth of strong oxidizing long‐lived reactive species. This study validates the sterilization efficacy of cold atmospheric plasma in practical cold‐chain environment, critical for curbing infectious disease transmission.

Effect of direct plasma treatment and plasma‐treated liquid on cutaneous squamous cell carcinoma: A proof‐of‐concept study

AbstractThis study investigates the efficacy of cold atmospheric plasma (CAP) in treating squamous cell carcinoma (SCC), a highly metastatic cancer. To assess the anticancer activity, two CAP treatment methods—direct treatment and indirect treatment (plasma‐treated N‐acetyl cysteine solution)—were used. Results indicate that both methods selectively target SCC cells, inducing oxidative and nitrosative stress, leading to decreased metabolic activity and increased apoptosis. Furthermore, a critical feature of cancer cells, metastatic behavior is also inhibited by CAP treatment. Coculture experiments demonstrate the effectiveness of CAP treatment in selectively inactivating SCC cells while leaving healthy cells unaffected. These findings suggest the potential use of CAP as a selective and effective treatment for SCC.

Antibacterial Efficacy of Cold Atmospheric Plasma, Photodynamic Therapy with Two Photosensitizers, and Diode Laser on Primary Mandibular Second Molar Root Canals Infected with Enterococcus faecalis: An In Vitro Study.

This study aimed to compare the antibacterial efficacy of cold atmospheric plasma (CAP), photodynamic therapy (PDT) with two photosensitizers (PSs), and diode laser for disinfection of primary mandibular second molar root canals infected with Enterococcus faecalis (E. faecalis). In this in vitro experimental study, 50 primary second primary molars underwent chemomechanical preparation of root canals. The root canals were then inoculated with E. faecalis. After 3 weeks of incubation, the teeth were randomly assigned to five groups of CAP, 940 nm diode laser, PDT with 445 nm laser and curcumin PS, PDT with 660 nm laser and methylene blue (MB) PS, and 2.5% sodium hypochlorite (NaOCl). Samples were collected from the vortexed root canals and cultured on agar, and the number of colonies was counted. Data were analyzed by one-way analysis of variance. The percentage of reduction in bacterial count was significantly different among the study groups (P < 0.001). The highest reduction in bacterial count was noted in 2.5% NaOCl and the lowest in 940 nm diode laser group. The difference in bacterial count reduction between 445 nm laser + curcumin and 660 nm laser + MB (P = 0.989), and CAP and NaOCl (P = 1.000) groups was not significant. CAP was found to be more effective than PDT and diode laser as an adjunct to mechanical root canal disinfection of primary molars for elimination of E. faecalis and can serve as an alternative to 2.5% NaOCl irrigation.

The Efficacy of Cold Atmospheric Plasma Deposited Antibiotics on Titanium Surfaces and Their Elution Liquids Against Staphylococcus aureus Growth Over Time

Cold atmospheric plasma (CAP) was used to deposit antibiotics, penicillin, and ciprofloxacin, separately onto titanium coupons. The antibiotic coating parameters were varied using a design of experiment software which factored in plasma power, bacterial and antibiotic load. The antimicrobial activity of the plasma deposited antibiotics was benchmarked against conventional spray coated materials and the effect of the plasma exposure is discussed. The deposited antibiotics were characterized using various surface analysis and microbiological techniques. It was found that the antibiotics were not degraded and retained antibiotic activity against planktonic &lt;i&gt;Staphylococcus aureus&lt;/i&gt; bacteria. However, the presence of the plasma during coating did alter the elution profile of the antibiotics and helped prolong the activity of the antibiotics on the metal surface. This study may contribute to the development of novel implant coating procedures that can offer prolonged antimicrobial protection.

A comparative study on the antifungal efficacy of cold atmospheric plasma at low and high surface density on Aspergillus chevalieri and mechanisms of action

Cold atmospheric plasma (CAP) is a promising innovative technology for microbial inactivation on food surfaces. In this study, we evaluated the potential of CAP at low (CAP-O3) and high (CAP-NOx) power using Aspergillus chevalieri as a fungal model, one of the most xerophilic and xerotolerant molds causing food spoilage, We observed a strong reduction in mycelial growth (60%) and conidial germination (90%) after 30 min of CAP-NOx, while CAP-O3 was less effective showing no reduction in mycelia growth and only 36% of spore germination reduction. Furthermore, cell death was accompanied by a loss of cellular and mitochondrial potential membrane, a significant (p < 0.05) increase in intracellular ROS, RNS, calcium, and DNA damage. For the first time, we reported that trehalose, glycerol, chitin and glucan accumulation are some adaptive mechanisms of A. chevalieri to counteract CAP stress, with CAP-NOx treatments inducing a major accumulation of these two osmolites. Our results suggested that Cold atmospheric plasma-induced cell death can be explained by oxidative stress-dependent through a cascade of reactions initiated by membrane depolarization.

Efficacy of cold atmospheric plasma for inactivation of viruses on raspberries

In this study, the effectiveness of cold atmospheric plasma (CAP) in inactivating murine norovirus (MNV/human norovirus surrogate) and hepatitis A virus (HAV) on aerosol-inoculated dark red Willamette raspberries was explored. Pulsed positive corona discharge system fed by synthetic air was used for the production of CAP. Raspberries were treated for 1, 3, 5, 7, and 10 min at 25 W. Application of CAP enabled a 4 log10 infectivity reduction in <5 min for MNV and approximately 10 min for HAV (from starting level of 6.91 and 7.84 log10 PFU/mL, respectively). Viral genome copies reduction of 3.18 log10 for MNV and 4.32 for HAV were found from starting level of 5.76 and 6.47 log10 gc/μL, respectively. CAP treatment did not result in significant degradation of fruit color, an important quality attribute. The study demonstrated CAP as an efficient post-harvest decontamination method to reduce viral load in raspberries without significantly affecting its quality parameters. Industrial relevanceDue to the fast-processing paces required in the raspberry industry, it is difficult to assure the complete microbiological safety of this fruit. Cold atmospheric plasma is a practical, environmentally-friendly, non-thermal tool for the effective reduction of microbial pathogens. The model developed in this study demonstrated that CAP treatment of fresh raspberries not only inactivated hazardous enteric viruses in a short time (10 min) but also unaffected fruit color stability. The simplicity of described CAP design and low-cost inputs (air and electricity) enable the commercial application of inexpensive plasma chambers for continuous surface decontamination of large volumes of raspberries without bringing processing to a standstill.

Cold Atmospheric Plasma Targeting Hematological Malignancies: Potentials and Problems of Clinical Translation

Cold atmospheric plasma is an ionized gas produced near room temperature; it generates reactive oxygen species and nitrogen species and induces physical changes, including ultraviolet, radiation, thermal, and electromagnetic effects. Several studies showed that cold atmospheric plasma could effectively provoke death in a huge amount of cell types, including neoplastic cells, via the induction of apoptosis, necrosis, and autophagy. This technique seems able to destroy tumor cells by disturbing their more susceptible redox equilibrium with respect to normal cells, but it is also able to cause immunogenic cell death by enhancing the immune response, to decrease angiogenesis, and to provoke genetic and epigenetics mutations. Solutions activated by cold gas plasma represent a new modality for treatment of less easily reached tumors, or hematological malignancies. Our review reports on accepted knowledge of cold atmospheric plasma’s effect on hematological malignancies, such as acute and chronic myeloid leukemia and multiple myeloma. Although relevant progress was made toward understanding the underlying mechanisms concerning the efficacy of cold atmospheric plasma in hematological tumors, there is a need to determine both guidelines and safety limits that guarantee an absence of long-term side effects.

Cold atmospheric plasma for preventing infection of viruses that use ACE2 for entry.

Rational: The mutating SARS-CoV-2 potentially impairs the efficacy of current vaccines or antibody-based treatments. Broad-spectrum and rapid anti-virus methods feasible for regular epidemic prevention against COVID-19 or alike are urgently called for.Methods: Using SARS-CoV-2 virus and bioengineered pseudoviruses carrying ACE2-binding spike protein domains, we examined the efficacy of cold atmospheric plasma (CAP) on virus entry prevention.Results: We found that CAP could effectively inhibit the entry of virus into cells. Direct CAP or CAP-activated medium (PAM) triggered rapid internalization and nuclear translocation of the virus receptor, ACE2, which began to return after 5 hours and was fully recovered by 12 hours. This was seen in vitro with both VERO-E6 cells and human mammary epithelial MCF10A cells, and in vivo. Hydroxyl radical (·OH) and species derived from its interactions with other species were found to be the most effective CAP components for triggering ACE2 nucleus translocation. The ERα/STAT3(Tyr705) and EGFR(Tyr1068/1086)/STAT3(Tyr705) axes were found to interact and collectively mediate the effects on ACE2 localization and expression.Conclusions: Our data support the use of PAM in helping control SARS-CoV-2 if developed into products for nose/mouth spray; an approach extendable to other viruses utilizing ACE2 for host entry.

Hsa_circRNA_0040462: a sensor of cells' response to CAP treatment with double-edged roles on breast cancer malignancy.

Cold atmospheric plasma (CAP) represents a novel onco-therapeutic approach that has demonstrated its efficacy in many types of tumors. The efficacy of CAP is dose-dependent that determines the panel of tumors feasible for receiving CAP treatment under a certain parameter configuration. Identifying markers for easy and fast prognosis of tumors' sensitivity in response to CAP exposure is of critical value towards optimized therapeutic outcome, the lack of which has largely limited the translation of CAP into clinics. Circular RNAs represent a novel type of biomarkers for disease diagnosis that is featured by easy detection and stability. Through whole transcriptome sequencing, followed by in vitro validations, computational predictions and preliminary functional studies, we identified hsa_circRNA_0040462 as a sensor of breast cancer cells' response to CAP treatment. Yet we warrant the use of hsa_circRNA_0040462 as an onco-therapeutic target given its double-edged roles on breast cancer progression, i.e., suppressive on the growth and promotive on the migrative ability of triple negative breast cancer cells. Our study for the first time focused on markers prognostic of CAP's efficacy and tumors' sensitivity to CAP treatment under a certain parameter configuration, and reported hsa_circRNA_0040462 as a sensor of cells' response to CAP treatment. Also, the uncovered dual roles of hsa_circRNA_0040462 further advanced our knowledge on the complex yet critical regulatory functionalities of circular RNAs in cancer progression.

A Prospective, Randomised, Controlled, Split-Face Clinical Trial to Assess the Safety and the Efficacy of Cold Atmospheric Plasma in the Treatment of Acne Vulgaris

The increase in antibiotic resistance requires effective non-antibiotic therapies for acne. Cold atmospheric plasma (CAP) inactivates bacteria and improves wound healing, but its effect on acne has not been investigated. The objective of this controlled split-face study was to assess safety and efficacy of CAP in moderate acne. One side of the face received 8–10 treatments with cold helium plasma within 4–6 weeks; follow-up was two and four weeks thereafter. Acne lesions were counted, followed by global acne severity ratings. Of the 34 patients included, 29 completed the study. No serious adverse events occurred. The two facial sides did not significantly differ in the number of inflammatory and non-inflammatory lesions. An interaction effect of number and type of treatment was found for inflammatory lesions. Lesion reduction after 10 treatments was significantly higher on the treated than on the untreated side. Percentage of patients reporting improved aesthetics was higher for the treated than for the untreated side after treatment completion (79% vs. 45%) and at the two- (72% vs. 45%) and four-week follow-up (79% vs. 52%). In conclusion, CAP was safe with excellent tolerability, showed moderate reduction in acne lesions and led to higher patient-based ratings of aesthetics than non-treatment.

Cold Atmospheric Plasma Promotes Regeneration-Associated Cell Functions of Murine Cementoblasts In Vitro.

The aim of the study was to examine the efficacy of cold atmospheric plasma (CAP) on the mineralization and cell proliferation of murine dental cementoblasts. Cells were treated with CAP and enamel matrix derivates (EMD). Gene expression of alkaline phosphatase (ALP), bone gamma-carboxyglutamate protein (BGLAP), periostin (POSTN), osteopontin (OPN), osterix (OSX), collagen type I alpha 1 chain (COL1A1), dentin matrix acidic phosphoprotein (DMP)1, RUNX family transcription factor (RUNX)2, and marker of proliferation Ki-67 (KI67) was quantified by real-time PCR. Protein expression was analyzed by immunocytochemistry and ELISA. ALP activity was determined by ALP assay. Von Kossa and alizarin red staining were used to display mineralization. Cell viability was analyzed by XTT assay, and morphological characterization was performed by DAPI/phalloidin staining. Cell migration was quantified with an established scratch assay. CAP and EMD upregulated both mRNA and protein synthesis of ALP, POSTN, and OPN. Additionally, DMP1 and COL1A1 were upregulated at both gene and protein levels. In addition to upregulated RUNX2 mRNA levels, treated cells mineralized more intensively. Moreover, CAP treatment resulted in an upregulation of KI67, higher cell viability, and improved cell migration. Our study shows that CAP appears to have stimulatory effects on regeneration-associated cell functions in cementoblasts.

Safety and efficacy of cold atmospheric plasma for the sterilization of a Pasteurella multocida–contaminated subcutaneously implanted foreign body in rabbits

To determine whether a stainless steel implant sterilized with a novel cold atmospheric plasma sterilization (CAPS) device adversely affects local tissues in rabbits and whether CAPS was as effective as steam sterilization with an autoclave to inactivate Pasteurella multocida. 31 healthy New Zealand White rabbits. Steam-autoclaved stainless steel implants inoculated with P multocida underwent a second steam autoclave sterilization (AIA) or CAPS (AICAPS). One AIA implant and 3 AICAPS implants were randomly placed subcutaneously at 4 sites in 21 rabbits (84 implants). These rabbits were monitored daily for 5 days for evidence of systemic illness and local tissue reactions at the implantation sites and then euthanized. Samples were taken from each implant site for bacterial culture and histologic examination. Cultures of samples obtained from all sites were negative for bacterial growth. No significant difference was observed in mean skin thickness or erythema between AIA and AICAPS implant sites on any observed day. Also, individual histologic grades for the epidermis, dermis, subcutis, and muscle and total histologic grade were not significantly different between AIA and AICAPS implant sites. Cold atmospheric plasma sterilization was noninferior to steam sterilization of P multocida-contaminated stainless steel implants in the rabbits in the present study. However, studies of the efficacy of CAPS for inactivation of other important bacteria are needed.

Safety and bactericidal efficacy of cold atmospheric plasma generated by a flexible surface Dielectric Barrier Discharge device against Pseudomonas aeruginosa in vitro and in vivo

BackgroundCold atmospheric plasma (CAP), which is ionized gas produced at atmospheric pressure, could be a novel and potent antimicrobial therapy for the treatment of infected wounds. Previously we have shown that CAP generated with a flexible surface Dielectric Barrier Discharge (sDBD) is highly effective against bacteria in vitro and in ex vivo burn wound models. In the current paper, we determined the in vitro and in vivo safety and efficacy of CAP generated by this sDBD device.MethodsThe effect of CAP on DNA mutations of V79 fibroblasts was measured using a hypoxanthine–guanine-phosphoribosyltransferase (HPRT) assay. Furthermore, effects on cell proliferation, apoptosis and DNA damage in ex vivo burn wound models (BWMs) were assessed using immunohistochemistry. Next, 105 colony forming units (CFU) P. aeruginosa strain PAO1 were exposed to CAP in a 3D collagen-elastin matrix environment to determine the number of surviving bacteria in vitro. Finally, rat excision wounds were inoculated with 107 CFU PAO1 for 24 h. The wounds received a single CAP treatment, repeated treatments on 4 consecutive days with CAP, 100 µL of 1% (wt/wt) silver sulfadiazine or no treatment. Wound swabs and punch biopsies were taken to determine the number of surviving bacteria.ResultsExposure of V79 fibroblasts to CAP did not increase the numbers of mutated colonies. Additionally, the number of proliferative, apoptotic and DNA damaged cells in the BWMs was comparable to that of the unexposed control. Exposure of PAO1 to CAP for 2 min resulted in the complete elimination of bacteria in vitro. Contrarily, CAP treatment for 6 min of rat wounds colonized with PAO1 did not effectively reduce the in vivo bacterial count.ConclusionsCAP treatment was safe but showed limited efficacy against PAO1 in our rat wound infection model.

Antibacterial efficacy of cold atmospheric plasma against Enterococcus faecalis planktonic cultures and biofilms in vitro.

Nosocomial infections have become a serious threat in our times and are getting more difficult to handle due to increasing development of resistances in bacteria. In this light, cold atmospheric plasma (CAP), which is known to effectively inactivate microorganisms, may be a promising alternative for application in the fields of dentistry and dermatology. CAPs are partly ionised gases, which operate at low temperature and are composed of electrons, ions, excited atoms and molecules, reactive oxygen and nitrogen species. In this study, the effect of CAP generated from ambient air was investigated against Enterococcus faecalis, grown on agar plates or as biofilms cultured for up to 72 h. CAP reduced the colony forming units (CFU) on agar plates by > 7 log10 steps. Treatment of 24 h old biofilms of E. faecalis resulted in CFU-reductions by ≥ 3 log10 steps after CAP treatment for 5 min and by ≥ 5 log10 steps after CAP treatment for 10 min. In biofilm experiments, chlorhexidine (CHX) and UVC radiation served as positive controls and were only slightly more effective than CAP. There was no damage of cytoplasmic membranes upon CAP treatment as shown by spectrometric measurements for release of nucleic acids. Thus, membrane damage seems not to be the primary mechanism of action for CAP towards E. faecalis. Overall, CAP showed pronounced antimicrobial efficacy against E. faecalis on agar plates as well as in biofilms similar to positive controls CHX or UVC.