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Despite adherence to endoscope reprocessing guidelines, biofilm has been detected in endoscope channels and has been associated with outbreaks of infection.1–4 This study published in the Journal of Hospital Infection compared an automated endoscope channel cleaner (AECC) with current standard of care for cleaning endoscopes, manual cleaning, to remove cyclic-buildup biofilm from simulated endoscope channels.
Microorganisms can coexist in complex structures called biofilm.5 These form in layers containing single- or multi-species bacteria and organic matter.6,7 Biofilms can adhere to endoscope surfaces and shield bacteria from cleaning, disinfection and drying.6
This poses a serious risk of infection transmission to patients undergoing endoscopic procedures, especially if the biofilm contains multidrug-resistant organisms.4,8 As such, effective biofilm removal is essential to ensure adequate disinfection or sterilisation of endoscopes.
The biofilm for this study was grown using the cyclic-buildup biofilm (CBB) model based on Ribeiro et al.9 This model simulated biofilm accumulation over repeated cycles of clinical use and reprocessing. The CBB was grown in polytetrafluoroethylene (PTFE) tubes corresponding to endoscope channels of different internal diameters: 3.7 mm for suction/biopsy channels, and 1.4 mm for air-water (AW) and auxiliary (AUX) channels. Biofilm growth in 1.4 mm diameter tubes was possible with modifications to the CBB model.
Both cleaning methods were assessed on their efficacy in removing CBB in PTFE tubes, representative of endoscope channels. Manual cleaning (MC) was performed according to the endoscope and detergent instructions for use (IFU). AW/AUX channels have narrow diameters that make them inaccessible to brushes. As such and in line with the IFU, the simulated AW/AUX channels were not brushed in this study.
The automated endoscope channel cleaner (AECC) was used according to the manufacturer's IFU. The AECC device used a specially formulated cleaning agent which was propelled through all channels at high velocity for cleaning. Residual protein, total organic carbon (TOC), and viable bacteria were measured after cleaning. These results were then compared to available internationally recognised alert levels for these cleaning markers (ISO 15883-5:2021).
The AECC demonstrated significant efficacy over MC in removing CBB biomarkers (protein, total organic carbon [TOC] and viable bacteria) from all simulated channel types (P<0.001). With a significant difference observed between the AECC and MC in removing viable bacteria from both 3.7 mm and 1.4 mm diameter channels (P<0.001).
While MC reduced protein and TOC to below alert levels in 3.7 mm diameter channels, CBB remained above alert levels in 1.4 mm diameter channels. Residues in the 1.4 mm channels exceeded the alert levels by greater than 10 times for protein and greater than 3 times for TOC. More than 106 cfu/cm² of viable P. aeruginosa and E. faecalis remained in 1.4 mm channels following MC. The stark contrast in results may be attributed to the fact that AW/AUX channels were not brushed. These channels have narrow diameters which generally makes them inaccessible to brushes. However, the AECC can be applied to channels of all diameters.
The AECC is a new approach which delivers physical cleaning to channels of various diameters. This study was able to demonstrate the AECC’s efficacy in removing CBB as quantified by reductions in biomarkers from simulated channels, which depending on diameter, may go unbrushed during MC. In clinical practice, MC is performed under time constraints and reprocessing staff may not fully adhere to the IFUs. Whereas MC in this study was performed with rigorous adherence to IFUs, which may not reflect the variability seen in clinical practice. Therefore, it is possible that results from MC in clinical practice, differ from those observed in this study. Although future clinical studies are necessary to further corroborate these findings, the AECC shows promise as a technology to clean biofilm from endoscope channels.
Moshkanbaryans L, Shah V, Tan LY, et al. Comparison of two endoscope channel cleaning approaches to remove cyclic build-up biofilm. J Hosp Infect. 2024;150:91-95.
Lia Moshkanbaryans, Vaibhav Shah, Lit Yeen Tan, Michael P. Jones, Karen Vickery, Michelle Alfa and Jon Burdach work at the crossroads of clinical and laboratory research and real-world outcomes in the areas of medical device cleaning and disinfection.
L.M., V.S., L.Y.T. and J.B. are employees of and hold stock in Nanosonics Ltd. M.P.J., K.V. and M.A. have received consulting fees from Nanosonics Ltd. This study was funded by Nanosonics Ltd, Sydney, Australia.