Pseudomonas aeruginosa biofilm decontamination and removal by Ar/H2O cold atmospheric plasma in endoscope-like tubing

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Abstract In medical device disinfection, removing bacteria and biofilms is challenging due to the poor penetration of detergents into the biofilm matrix. This is specifically true for endoscopes, which cannot be fully sterilized. This paper presents a new technique for decontaminating and removing P. aeruginosa biofilm from endoscope tubing using cold atmospheric plasma (CAP). The CAP is produced everywhere inside a contaminated tube under sustained Ar/H2O flow. The tube arrangement mimics the working channel environment of an endoscope, which is particularly difficult to sterilize. The discharge’s chemical activity was optimized by increasing the voltage without increasing the total power, which enhanced the production of hydroxyl radicals (OH) and hydrogen peroxide (H2O2). The disinfection treatment was tested on 24 h grown biofilm using the crystal violet assay for biofilm removal and the regrowth assay for bacterial decontamination. The treatments demonstrated effective decontamination capabilities at all treatment times with no bacterial regrowth. Etching of the biofilm sample by OH radicals was observed. After 30 min of treatment, only 18 ± 4% of biofilm remained on the surface, indicating near-complete biofilm removal and total absence of bacterial regrowth. This preliminary study demonstrates the effectiveness of using the direct contact of an Ar/H2O plasma to decontaminate and remove biofilm from complex shapes, such as flexible polytetraethylene tubes. It has the potential to enhance and shorten the disinfection of medical equipment, such as endoscopes.