Bacterial bioluminescence for the real time and <i>in situ</i> monitoring of endoscope disinfection using plasma activated water

Endoscope reprocessing is a time-consuming, multi-step process, and ongoing microbial surveillance is necessary to ensure effective reprocessing and safe storage. Despite this, traditional surveillance methods, such as cultures, are not often carried out due to time and cost constraints, providing only delayed end point results from specific locations, with no insight into biofilm formation, disinfection efficacy, or any variability related to device design. Within this study, the efficacy of plasma activated water (PAW) disinfection (and subsequent regrowth) within endoscopic test pieces was investigated using bacterial bioluminescence enabling real time and <i>in situ</i> monitoring of biofilm formation and treatment efficacy. Real time imaging of bioluminescent <i>Pseudomonas aeruginosa</i> PAO1 SEI MCS5-lite was used to track biofilm growth within translucent PVC endoscopic test pieces across regions of interest using analysis of bioluminescent intensity. Results demonstrated that biofilm accumulation was more prominent around connectors compared to other regions of the test pieces. Disinfection with PAW achieved a significant 96.45% reduction in biofilm density (determined by culture) and a 93.08% reduction in bioluminescence (relative light units). However, percentage reduction in bioluminescence ranged from 77% to 95% across regions indicating lack of uniformity of treatment. Subsequent testing with plasma activated disinfectant (PAD) showed consistent biofilm reduction across all regions, with no variability between connectors and other regions as observed with PAW and other treatments. In conclusion, bioluminescence can be used to assess efficacy of disinfectants and effect of endoscope design by tracking biofilm density in real time and <i>in situ</i>.