In vitro evaluation of the decontamination effect of cold argon plasma on selected bacteria frequently encountered in small animal bite injuries

Abstract

27Objective: The beneficial effects of cold argon plasma (CAP) on wound healing and its 28 capacity for bacterial decontamination has recently been documented. However, despite 29 favourable reports from experimental trials and human applications, the first in vivo studies in 30 small animals did not prove any decontamination effect in canine bite wounds. 31 The present study therefore aimed to evaluate the decontamination effect of CAP in different 32 bacteria frequently encountered in canine bite wounds in vitro. 33 Methods: Standard strains of Escherichia (E.) coli, Staphylococcus (S.) pseudintermedius, S. 34 aureus, Streptococcus (Sc.) canis, Pseudomonas (P.) aeruginosa and Pasteurella multocida 35were investigated. To evaluate the influence of the bacterial growth phase, each bacterium 36 was incubated in nutrient broth for 3 and 8 hours, respectively, before argon plasma treatment. 37Three different bacterial concentrations were created per bacterium and growth phase, and 38 each was exposed to cold plasma at a gas flow rate of 5 standard litres/minute of argon for 30 39 seconds, 1 minute and 2 minutes. 40 Results: Argon treatment resulted in acceptable decontamination rates (range 98.9-99.9%) in 41 all bacteria species in vitro; however, differences in susceptibility were detected in the 42 different tested bacteria. Treatment time significantly (P<0.05) correlated with the 43 decontamination rate in E. coli, Sc. canis and S. aureus, with an exposure time of 2 minutes 44 being most effective. The initial bacterial concentration significantly (P<0.05) influenced 45 decontamination in Pasteurella multocida and P. aeruginosa, in which treatment time was not 46 as important. The growth phase only influenced decontamination in S. pseudintermedius. 47 Conclusion: CAP exerts effective antibacterial activity against the tested bacteria strains in 48 vitro, with species specific effects of treatment time, growth phase and concentration. 49 50 Keywords: cold argon plasma, bacterial decontamination, time-dependent effects, 51 concentration-dependent effects, bacterial growth 53 Microbial multidrug-resistance (MDR) is one of the main issues that must be solved by 54 modern medicine [1,2,3]. Among surgical patients, surgical site infections, and especially 55 open wounds, represent risk groups, and antibiotic treatment frequently results in a shift to 56 more resistant bacteria rather than in wound decontamination [1,3,4]. Recognition of this 57 problem has increased research on alternative strategies for wound decontamination, 58 including antiseptic substances and physical treatment options in human medicine [5,6]. 59 However, despite the fact that the same problem exists in small animal surgical patients [1,3], 60 there is a paucity of studies focusing on antiseptic wound treatment in veterinary medicine. 61 Numerous in vitro and in vivo trials in small mammals and humans have documented an 62 effective decontamination effect combined with a wide safety margin regarding a damage of 63 eukaryotic cells for CAP [7]...

In vitro evaluation of the decontamination effect of cold atmospheric argon plasma on selected bacteria frequently encountered in small animal bite injuries

“…We think that this effect represents the most important clinical limitation. If the results of the study by Winter et al (2018) are interpreted under the light of our current findings, we think that the usage of bigger devices, which allow appropriate treatment time under clinical conditions, would most likely improve performance in vivo.…”

“…However, the first study evaluating its effect in bite wounds in dogs did not find any decontaminating effect in vivo at all (Winter et al 2018). Based on the beneficial results in experimental and human applications, this finding seems peculiar.…”

“…Fernandez et al (2012) could show, that inactivation of Salmonella Typhimurium through CAP treatment is more efficient, the lower the initial bacterial concentration is. Despite these well-investigated facts, the first clinical trials evaluating the decontaminating effect of CAAP in canine bite wounds were not able to detect any decontamination effects in vivo (Winter et al 2018). Therefore, it was our aim to investigate the effect of the used CAAP source in bacteria to be anticipated in canine bite wounds in vitro to document the in vitro efficacy and potential influencing factors with respect to bacteria species, bacteria growth phase and bacteria concentration.…”