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Objectives To compare the efficacy of polyhexanide, cold argon plasma and saline in reducing bacterial bio‐burden in dog bite wounds. Materials and Methods Prospective blinded randomised clinical trial. Dogs were randomly assigned to one of the treatment groups by lottery and bacterial cultures obtained before and after treatment were compared. Bite wounds were surgically debrided and treated with polyhexanide, cold argon plasma or saline lavage. All wounds were cultured three times: directly after debridement, directly after prelavage with 2 mL/cm2 (saline in the saline and cold argon plasma group, or polyhexanide) and following the definitive lavage. Data were analysed using a generalised linear model for ordinal data. Results A total of 85 dogs were enrolled in this study (polyhexanide n=29, cold argon plasma n=28, saline n=28). Positive bacterial culture results after debridement were obtained in 53/85 (62.3%) wounds. Polyhexanide and saline lavage significantly reduced the bio‐burden, while cold argon plasma treatment did not. This effect was evident after prelavage when polyhexanide performed significantly better than saline and cold argon plasma as well as after final treatment. No significant differences were detected after prelavage or main treatment between saline and cold argon plasma. Clinical Significance Polyhexanide lavage achieved the best immediate and ultimate decontamination of bite wounds.

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Zusammenfassung Ziel der Studie war, die Keimbelastung sowie die klinische Effizienz von Polyhexanid, Argon-Kaltplasma und Kochsalzlösung zur Reduktion der Bioburden bei Hundebissverletzungen zu überprüfen. Material und Methoden: In die Studie eingeschlossen wurden Hunde mit Bissverletzungen, die durch ein chirurgisches Debridement mit anschließender Wundbehandlung durch Lavage mit Polyhexanid-Biguanid (A), Therapie mit kaltem Argonplasma (B) oder Lavage mit physiologischer Kochsalzlösung (C) versorgt wurden. Ein bakterieller Abstrich erfolgte bei allen Patienten nach Debridement sowie nach der Lavage bzw. Behandlung mit Argon-Kaltplasma. Zur Auswertung der Resultate diente der Chi-Quadrat-Test. Ergebnisse: Insgesamt 40 Hunde gingen in die Studie ein (A: n = 12; B: n = 10; C: n = 18). Bei einem Großteil der Verletzungen handelte es sich um geringfügige Bisswunden. Ein Keimnachweis ergab sich bei 87,5% aller Patienten, wobei 19,8% aller Isolate als multiresistent klassifiziert wurden. Eine Reduktion der Keimlast durch Lavage wurde bei 8/12 Hunden der Gruppe A, 5/10 Hunden der Gruppe B und 14/18 Hunden der Gruppe C erreicht. Eine komplette Dekontamination durch Lavage gelang bei 5/12 Hunden der Gruppe A, 2/10 der Gruppe B und 9/18 der Gruppe C. Statistisch signifikante Unterschiede oder Effekte auf spätere Komplikationen waren nicht festzustellen. Schlussfolgerung: Zwischen den verschiedenen Lavagekonzepten bestanden keine statistisch signifikanten Unterschiede, doch wurde in der Kaltplasma-Gruppe die geringste Dekontamination erzielt. Klinische Relevanz: Bei Bissverletzungen ist von einer hohen Keimbelastung auszugehen. Zudem werden zunehmend multiresistente Isolate nachgewiesen. Basierend auf diesen ersten Ergebnissen ließ sich keine Überlegenheit von Polyhexanid oder Kaltplasma gegenüber physiologischer Kochsalzlösung zur Wundlavage nachweisen.

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]...