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Die Inaktivierung von Bakterien durch Antiseptika, z. B. auf chronischen Wunden ist unter anderem aufgrund der Bildung von Biofilmen erschwert. Ebenso stellt die Entwicklung von Resistenzen gegenüber Antibiotika ein immer größer werdendes Problem bei der Behandlung von Infektionen dar. Zudem ist die antimikrobielle Behandlung nur ein Teilaspekt, um chronisch infizierte Wunden in einen regenerativen Heilungsprozess zu überführen. Daher sind neue, alternative Behandlungsstrategien von hoher Bedeutung. Hierfür scheint physikalisches Plasma aufgrund seiner antimikrobiellen wie auch wundheilungsfördernder Wirkungsweise eine aussichtsreiche Perspektive darzustellen. Zur Erzeugung von sog. Tissue Tollerablen Plasma (TTP) stehen verschiedene Plasmaquellen zur Verfügung, die zur Anwendung gegen Mikroorganismen in Biofilmen in Frage kommen. In der vorliegenden Arbeit wurden der kinpen09 und zwei Dielektrisch-Behinderte-Oberflächen-Entladungs-Quellen, die Conplas- und die Epoxidharz-Plasmaquelle, auf ihre antimikrobielle Wirkungsweise mit Argonplasma mit und ohne Sauerstoffbeimischung und mit Luftplasma v. a. an Biofilmen mit P. aeruginosa SG81 und S. epidermidis RP62A untersucht. Mit dem kinpen09 wurde zusätzlich die antimikrobielle Effektivität von Plasma mit Helium oder Stickstoffbeimischungen getestet. Bei Einsatz des kinpen09 zeigte sich Argon als das antimikrobiell effektivste Trägergas. Bei der Epoxidharz-Plasmaquelle war Luftplasma am wirksamsten. Bei der Conplas sind Luft- und Argonplasma etwa gleich effizient gegen mikrobielle Biofilme. Die Reduktionsraten bei Argonplasma mit dem kinpen09 und Conplas lagen nach 300 s Expositionszeit bei P. aeruginosa bei ca. 5 log10 und mit dem kinpen09 bei S. epidermidis bei 3 log10. Diese Reduktionsraten übersteigen mit Ausnahme von 300 s Ar+O2-Plasma (kinpen09) die Wirksamkeit von Chlorhexidin (0,1 %), einem Standard-Antiseptikum zur Behandlung von Biofilmen, nach 10 min Behandlungsdauer von ca. 1,5 log10 signifikant (p < 0,005). In Übereinstimmung zur Literatur lässt sich aus den Ergebnissen ableiten, dass v. a. Sauerstoffradikale für die antimikrobielle Wirksamkeit verantwortlich sind. Neben der alleinigen Anwendung von TTP könnten Kombinationsbehandlungen mit Antiseptika aussichtsreiche Verfahren zur gezielten Inaktivierung von Mikroorganismen in Biofilmen und zur Modulation von Wundheilungsprozessen darstellen.
Previous studies on the antimicrobial activity of cold atmospheric pressure argon plasma showed varying effects against mecA<sup>+</sup> or mecA<sup>-</sup>Staphylococcus aureus strains. This observation may have important clinical and epidemiological implications. Here, the antibacterial activity of argon plasma was investigated against 78 genetically different S. aureus strains, stratified by mecA, luk-P, agr1-4, or the cell wall capsule polysaccharide types 5 and 8. kINPen09® served as the plasma source for all experiments. On agar plates, mecA<sup>+</sup>luk-P<sup>-</sup>S. aureus strains showed a decreased susceptibility against plasma compared to other S. aureus strains. This study underlines the high complexity of microbial defence against antimicrobial treatment and confirms a previously reported strain-dependent susceptibility of S. aureus to plasma treatment.
Because of some disadvantages of chemical disinfection in dental practice (especially denture cleaning), we investigated the effects of physical methods on Candida albicans biofilms. For this purpose, the antifungal efficacy of three different low-temperature plasma devices (an atmospheric pressure plasma jet and two different dielectric barrier discharges (DBDs)) on Candida albicans biofilms grown on titanium discs in vitro was investigated. As positive treatment controls, we used 0.1% chlorhexidine digluconate (CHX) and 0.6% sodium hypochlorite (NaOCl). The corresponding gas streams without plasma ignition served as negative treatment controls. The efficacy of the plasma treatment was determined evaluating the number of colony-forming units (CFU) recovered from titanium discs. The plasma treatment reduced the CFU significantly compared to chemical disinfectants. While 10 min CHX or NaOCl exposure led to a CFU log10 reduction factor of 1.5, the log10 reduction factor of DBD plasma was up to 5. In conclusion, the use of low-temperature plasma is a promising physical alternative to chemical antiseptics for dental practice.
Objectives
Biofilm removal is the decisive factor for the control of peri-implantitis. Cold atmospheric pressure plasma (CAP) can become an effective aid due to its ability to destroy and to inactivate bacterial biofilm residues. This study evaluated the cleaning efficiency of CAP, and air-polishing with glycine (APG) or erythritol (APE) containing powders alone or in combination with CAP (APG + CAP, APE + CAP) on sandblasted/acid etched, and anodised titanium implant surface.
Materials and methods
On respective titanium discs, a 7-day ex vivo human biofilm was grown. Afterwards, the samples were treated with CAP, APG, APE, APG + CAP, and APE + CAP. Sterile and untreated biofilm discs were used for verification. Directly after treatment and after 5 days of incubation in medium at 37 °C, samples were prepared for examination by fluorescence microscopy. The relative biofilm fluorescence was measured for quantitative analyses.
Results
Air-polishing with or without CAP removed biofilms effectively. The combination of air-polishing with CAP showed the best cleaning results compared to single treatments, even on day 5. Immediately after treatment, APE + CAP showed insignificant higher cleansing efficiency than APG + CAP.
Conclusions
CAP supports mechanical cleansing and disinfection to remove and inactivate microbial biofilm on implant surfaces significantly. Here, the type of the powder was not important. The highest cleansing results were obtained on sandblasted/etched surfaces.
Clinical relevance.
Microbial residuals impede wound healing and re-osseointegration after peri-implantitis treatment. Air-polishing treatment removes biofilms very effectively, but not completely. In combination with CAP, microbial free surfaces can be achieved. The tested treatment regime offers an advantage during treatment of peri-implantitis.
Background
Peri-implantitis therapy is a major problem in implantology. Because of challenging rough implant surface and implant geometry, microorganisms can hide and survive in implant microstructures and impede debridement. We developed a new water jet (WJ) device and a new cold atmospheric pressure plasma (CAP) device to overcome these problems and investigated aspects of efficacy in vitro and safety with the aim to create the prerequisites for a clinical pilot study with these medical devices.
Methods
We compared the efficiency of a single treatment with a WJ or curette and cotton swab (CC) without or with adjunctive use of CAP (WJ + CAP, CC + CAP) to remove biofilm in vitro from rough titanium discs. Treatment efficacy was evaluated by measuring turbidity up to 72 h for bacterial re-growth or spreading of osteoblast-like cells (MG-63) after 5 days with scanning electron microscopy. With respect to application safety, the WJ and CAP instruments were examined according to basic regulations for medical devices.
Results
After 96 h of incubation all WJ and CC treated disks were turbid but 67% of WJ + CAP and 46% CC + CAP treated specimens were still clear. The increase in turbidity after WJ treatment was delayed by about 20 h compared to CC treatment. In combination with CAP the cell coverage significantly increased to 82% (WJ + CAP) or 72% (CC + CAP), compared to single treatment 11% (WJ) or 10% (CC).
Conclusion
The newly developed water jet device effectively removes biofilm from rough titanium surfaces in vitro and, in combination with the new CAP device, biologically acceptable surfaces allow osteoblasts to grow. WJ in combination with CAP leads to cleaner surfaces than the usage of curette and cotton swabs with or without subsequent plasma treatment. Our next step will be a clinical pilot study with these new devices to assess the clinical healing process.
Peri-implantitis-associated inflammation can lead to bone loss and implant failure. Current decontamination measures are ineffective due to the implants’ complex geometry and rough surfaces providing niches for microbial biofilms. A modified water jet system (WaterJet) was combined with cold plasma technology (CAP) to achieve superior antimicrobial efficacy compared to cotton gauze treatment. Seven-day-old multi-species-contaminated titanium discs and implants were investigated as model systems. The efficacy of decontamination on implants was determined by rolling the implants over agar and determining colony-forming units supported by scanning electron microscopy image quantification of implant surface features. The inflammatory consequences of mono and combination treatments were investigated with peripheral blood mononuclear cell surface marker expression and chemokine and cytokine release profiles on titanium discs. In addition, titanium discs were assayed using fluorescence microscopy. Cotton gauze was inferior to WaterJet treatment according to all types of analysis. In combination with the antimicrobial effect of CAP, decontamination was improved accordingly. Mono and CAP-combined treatment on titanium surfaces alone did not unleash inflammation. Simultaneously, chemokine and cytokine release was dramatically reduced in samples that had benefited from additional antimicrobial effects through CAP. The combined treatment with WaterJet and CAP potently removed biofilm and disinfected rough titanium implant surfaces. At the same time, non-favorable rendering of the surface structure or its pro-inflammatory potential through CAP was not observed.