The potential benefits of an automated flexible endoscope channel brushing system for manual cleaning of endoscopes

Contaminated endoscopes have resulted in numerous infectious outbreaks of multidrug-resistant microorganisms in past decades, including those with carbapenem-resistant Enterobacteriaceae [1]. Outbreaks are caused by failure to properly reprocess reusable endoscopes, leading to persistent endoscope contamination and patient exposure to potentially pathogenic microorganisms. Such outbreaks occurred even though no reprocessing lapses or endoscope defects were identified [1]. Despite numerous attempts to control the issue, to date patient-ready reusable duodenoscopes remain contaminated with gastrointestinal microflora in approximately 15 % of cases [2]. Moreover, endoscope contamination is not confined to the use of duodenoscopes. A recent review reported that 28 % of gastroscope channels and 32 % of colonoscope channels are contaminated after reprocessing [3].

Endoscopes have a complex design with multiple narrow channels that make it challenging to clean them adequately. The use of automated endoscope reprocessors, recommended by most guidelines over manual disinfection, standardizes high-level disinfection [4]. However, manual cleaning of the endoscope before it is subjected to high-level disinfection remains a critical component of the overall cleaning process in order to decrease the bioburden; if not performed correctly, it can result in the build up of microorganisms and biofilm in endoscope channels [5]. Conventionally, manual cleaning is done by means of manually rinsing and brushing the endoscope channels. However, time pressure, dislike of the cleaning tasks and physical discomfort may result in omitted or faulty manual cleaning procedures [6].

“The result of an 8.2 percentage point decrease in positive cultures after automated brushing compared with conventional manual brushing is an important and clinically relevant finding.”

In the current issue of Endoscopy, Shang et al. evaluated the use of an automated flexible endoscope channel brushing system (AECBS), and compared its application with conventional manual brushing by assessing contamination rates of gastroscopes and colonoscopes [7]. The AECBS comprises a control module and a brushing module, which is attached to a drive module. The brushing module is connected to the endoscope by a guide connector that has three connectors. These connectors are used to introduce the brush into three different areas: 1) the suction port, 2) the control section, and 3) the instrument channel port. Every weekday, 10 endoscopes were randomly selected from the pool of 30 gastroscopes and 15 colonoscopes and allocated to either AECBS or manual brushing. The endoscopes were sampled after high-level disinfection and forced-air drying. Once sampled, the endoscope underwent a second cleaning in the AER and was then placed in quarantine until culture results were available. Endoscopes that tested positive were sampled and cleaned up to two additional times. If contamination persisted, the endoscope was sterilized using ethylene oxide gas. In total, 409 endoscope cultures were collected, 204 in the AECBS group and 205 in the manual group. The proportion of positive cultures was lower after AECBS compared with the manual group, both for any microorganism (15.2 % vs. 23.4 %; P = 0.04) and for high pathogenic microorganisms (4.9 % vs. 10.7 %; P = 0.03). A beneficial effect was only found for gastroscopes and not for colonoscopes.

The findings of this study demonstrate the potential to improve the hygiene of reusable endoscopes and reduce the risk of cross contamination through the implementation of innovative techniques. The result of an 8.2 percentage point decrease in positive cultures after automated brushing compared with conventional manual brushing is an important and clinically relevant finding. The benefit in colonoscopes, however, remains unclear, potentially due to the insufficient power of the study to investigate selected subgroups. Future research is needed to investigate the potential benefit in colonoscopes and other endoscope types such as duodenoscopes.

While the study provides valuable insights, there are some methodological aspects that are worth discussing. First, the authors may have underestimated the effect of AECBS. Prior to the study, they scrutinized their endoscope arsenal and excluded endoscopes that, in terms of relative reduction of bacterial load, would potentially benefit most from the intervention. Additionally, the protocol required endoscopes in the conservative group to be brushed three times, despite incomplete brushing (including too few cycles or omitting it entirely) being a well-known issue in daily clinical practice. The AECBS on the other hand, by virtue of its design, ensures consistency by eliminating the influence of interpersonal variation between reprocessing staff, including differences in the number of passes, brushing speed, strength, and time. Furthermore, if feasible, electronically documenting the completeness of brushing by the AECBS per cycle and per endoscope would generate a type of process control that provides a significant advantage over any manual process.

Unfortunately, the endoscope sampling and culture methods were not described, which limits the possibility of repeating or comparing the results of this study. It would also be worth knowing whether (repeated) cultures of the endoscopes at study entry were negative, precluding the potential presence of a persistent biofilm from the start.

Furthermore, the statistical tests used in the study do not consider the fact that repeated samples were taken from the same pool of endoscopes (405 endoscope cultures from a pool of 45 endoscopes averages 9 cultures per endoscope). This could result in potential bias because it does not account for within-group correlation. It is theoretically possible that certain individual endoscopes may be more likely to become contaminated than others. In this regard, it would also be useful to know whether there were “bad endoscopes” responsible for most of the positive cultures, which could indicate a persistent biofilm. Nonetheless, this would not necessarily undermine the potential of AECBS, as its application in new endoscopes may help prevent biofilm formation. Finally, it would have been valuable to perform multivariate analysis to determine the extent to which the effect on the contamination rate is explained by the longer brushing time of the AECBS.

Despite some methodological limitations, the study by Shang et al. shows that the application of AECBS is promising and signifies an opportunity to reduce endoscope contamination and its adherent risk for patients. The study also underscores the potential of innovative technology to further contain the contamination rate of reusable endoscopes. This is an important factor given that reusable endoscopy is here to stay for many years to come despite ongoing developments in single-use endoscopes.

Publication History

Article published online:
17 April 2023

• References

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