Decolonisation of MRSA, S. aureus and E. coli by Cold-Atmospheric Plasma Using a Porcine Skin Model In Vitro

Abstract

In the last twenty years new antibacterial agents approved by the U.S. FDA decreased whereas in parallel the resistance situation of multi-resistant bacteria increased. Thus, community and nosocomial acquired infections of resistant bacteria led to a decrease in the efficacy of standard therapy, prolonging treatment time and increasing healthcare costs. Therefore, the aim of this work was to demonstrate the applicability of cold atmospheric plasma for decolonisation of Gram-positive (Methicillin-resistant Staphylococcus aureus (MRSA), Methicillin-sensitive Staphylococcus aureus) and Gram-negative bacteria (E. coli) using an ex vivo pig skin model. Freshly excised skin samples were taken from six month old female pigs (breed: Pietrain). After application of pure bacteria on the surface of the explants these were treated with cold atmospheric plasma for up to 15 min. Two different plasma devices were evaluated. A decolonisation efficacy of 3 log10 steps was achieved already after 6 min of plasma treatment. Longer plasma treatment times achieved a killing rate of 5 log10 steps independently from the applied bacteria strains. Histological evaluations of untreated and treated skin areas upon cold atmospheric plasma treatment within 24 h showed no morphological changes as well as no significant degree of necrosis or apoptosis determined by the TUNEL-assay indicating that the porcine skin is still vital. This study demonstrates for the first time that cold atmospheric plasma is able to very efficiently kill bacteria applied to an intact skin surface using an ex vivo porcine skin model. The results emphasize the potential of cold atmospheric plasma as a new possible treatment option for decolonisation of human skin from bacteria in patients in the future without harming the surrounding tissue.

Terminal sterilization: Conventional methods versus emerging cold atmospheric pressure plasma technology for non‐viable biological tissues

“…Furthermore, no significant effects on living cell viability were reported. [111] In other studies, a slight reduction in viability through necrosis of in vitro culture of mucosal cells was observed, however, no mutagenic effects were observed. [136,141] The reason CAP mechanisms are generally harmless to human cells and tissue is attributed to CAP's superficial penetration [142] {Shintani, 2016 #459}, and potentially that multicellular eukaryotic tissues have more complicated mechanisms to enable survival of oxidative stresses introduced by plasma agents, than prokaryotic cells.…”

“…Examples reported of CAP capability for decontaminating multidrug resistant bacteria including the highly resistant MRSA [109][110][111] and Pseudomonas aeruginosa. [110] Notably, CAP is also effective on the sterilization resistant Deinococcus radiodurans bacteria.…”

“…[110] Notably, CAP is also effective on the sterilization resistant Deinococcus radiodurans bacteria. [112] Less resistant vegetative bacteria have also been tested against the antimicrobial activity of CAP, and were eliminated with different degrees of survival, including gramnegative: Escherichia coli [111,113,114] , Salmonella typhimuriu [115] , and gram-positive Staphylocuccus epidermidis [90,113,116] , Staphylococcus aureus [90,114] , Micrococcus luteus [95] , Streptococcus pyogenes [90] , Enterococcus faecalis [117] and Enterococcus faecium. [90] Gramnegative bacteria are more susceptible to gas plasma treatments than gram-positive [104,118] and differences in susceptibility are thought to be due to variation in the thickness of the peptidoglycan murein layer in the bacterial cell wall.…”

Inhibition of methicillin resistant Staphylococcus aureus by a plasma needle

“…Most studies have shown very good results [5][6][7][8] in direct contact of plasmas with microorganisms. However sterilization of planktonic samples and biofilms proved to be more difficult [9][10][11][12][13]. In this paper we extend the application of a plasma needle that has been tested in direct contact with plant and mammalian cells [14,15] and for planktonic samples of bacteria [15] to study sterilization of biofilms.…”

“…This explains one of the major advantages of cold atmospheric plasmas i.e. multiple targets in bacterial cells make the emergence of resistance mechanisms less likely [9]. In addition, plasma chemistry is important as generation of radicals or active molecules at the surface in very small quantities may trigger a biological response with only a small amount of reactive species that would otherwise be very toxic.…”