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Original article Clinical endoscopy: Editorial| Volume 93, ISSUE 4, P932-934, April 2021

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Enhanced reprocessing of duodenoscopes: A glass half full or half empty?

      Abbreviations:

      DHLD (double HLD), HLD (high-level disinfection), LCS (liquid chemical sterilization)
      Reports of duodenoscope-transmitted infections date back to at least 1987, when Allen et al
      • Allen J.I.
      • Allen M.O.C.
      • Olson M.M.
      • et al.
      Pseudomonas infection of the biliary system resulting from use of a contaminated endoscope.
      detailed an outbreak of Pseudomonas aeruginosa among 10 patients. Since this event, there have been many reports of duodenoscope-transmitted infections, often with multidrug-resistant organisms. To date, there have been at least 350 affected patients at 41 facilities since 2010.
      MAUDE - Manufacturer and User Facility Device Experience.
      Initially, outbreaks were attributed to nonadherence with guidelines from the U.S. Food and Drug Administration (FDA) and from manufacturers for endoscope inspection, manual cleaning, high-level disinfection (HLD), or storage. However, a closer examination contradicts this, with an FDA postmarketing surveillance study showing a 5.0% duodenoscope contamination rate with high-concern pathogens even after duodenoscopes have undergone manufacturer-approved reprocessing.
      The FDA Provides Interim Results of Duodenoscope Reprocessing Studies Conducted in Real-World Settings: FDA Safety Communication | FDA.
      In 2015, in response to several reports of these outbreaks involving carbapenem-resistant Enterobacteriaceae, the FDA recommended that 1 of 4 supplemental reprocessing measures be instituted to reduce future outbreaks involving duodenoscopes: surveillance culturing and quarantining, double HLD (DHLD), ethylene oxide gas sterilization, and liquid chemical sterilization (LCS).
      Safety Communications >Supplemental Measures to Enhance Duodenoscope Reprocessing: FDA Safety Communication.
      Because any infection resulting from duodenoscope transmission may be significant in terms of morbidity, mortality, cost, and societal trust in the health system, the hope was that these supplemental measures would help us “get to zero” and move us closer to eliminating these outbreaks altogether.
      • Tokar J.L.
      • Allen J.I.
      • Kochman M.L.
      Getting to zero: reducing the risk for duodenoscope-related infections.
      Unfortunately, randomized controlled trials comparing double HLD
      • Snyder G.M.
      • Wright S.B.
      • Smithey A.
      • et al.
      Randomized comparison of 3 high-level disinfection and sterilization procedures for duodenoscopes.
      ,
      • Bartles R.L.
      • Leggett J.E.
      • Hove S.
      • et al.
      A randomized trial of single versus double high-level disinfection of duodenoscopes and linear echoendoscopes using standard automated reprocessing.
      and ethylene oxide gas sterilization
      • Snyder G.M.
      • Wright S.B.
      • Smithey A.
      • et al.
      Randomized comparison of 3 high-level disinfection and sterilization procedures for duodenoscopes.
      with standard single HLD have not shown any significant benefit of these enhanced reprocessing methods compared with standard HLD. However, to date, a similar randomized controlled trial has not been performed comparing LCS with other currently used methods to reprocess duodenoscopes. Therefore, high-quality studies evaluating the benefits of these enhanced interventions are needed.
      In this issue of Gastrointestinal Endoscopy, Gromski et al
      • Gromski M.A.
      • Sieber M.S.
      • Sherman S.
      • et al.
      Double high-level disinfection versus liquid chemical sterilization for reprocessing of duodenoscopes used for ERCP: a prospective, randomized study.
      compared the efficacy of reprocessing duodenoscopes with either DHLD or LCS. The authors performed a prospective randomized trial where 67 duodenoscopes (Olympus models TJF-Q180 and TJF-160, Olympus America, Central Valley, Pa, USA) were randomized to undergo DHLD (Cantel DSD EDGE Dual Basin AER System, n = 34) or LCS (Steris 1E system, n = 33) over a 1-year study period. Furthermore, 10 older-model duodenoscopes (Olympus JF-130, JF-140, and TJF-140) were included in this analysis but were not randomized, and were all reprocessed with DHLD, given the institutional experience with DHLD on these less commonly used models. Duodenoscopes were randomly cultured after reprocessing with a goal for culturing to be performed after 30% of all ERCP procedures. During the 1-year study period, 453 cultures were drawn from the DHLD group and 425 cultures were drawn from the LCS group. In total, 17 of 878 cultures (1.9%) were positive for any organisms. There was no difference in rate of positive cultures between the DHLD (8/453; 1.8%) and LCS (9/425; 2.1%) groups (P = .8). Two cultures in each group had growth of high-concern organisms (0.4% vs 0.5%; P = 1). When the data from the older duodenoscopes were excluded, rates of positive cultures with any organisms (1.3% vs 2.1%; P = .6) and with high-concern organisms (0.5% vs 0.5%; P = 1) still did not differ significantly.
      • Gromski M.A.
      • Sieber M.S.
      • Sherman S.
      • et al.
      Double high-level disinfection versus liquid chemical sterilization for reprocessing of duodenoscopes used for ERCP: a prospective, randomized study.
      These findings indicated no additional benefit of LCS compared with DHLD in reducing the postreprocessing bacterial contamination risk of duodenoscopes.
      In comparison with prior studies of DHLD, including prior work published by this group,
      • Rex D.K.
      • Sieber M.
      • Lehman G.A.
      • et al.
      A double-reprocessing high-level disinfection protocol does not eliminate positive cultures from the elevators of duodenoscopes.
      the reported overall culture positivity rate (combining both high- and low-concern organisms) of 1.9% is low. There are several potential reasons for this. First, this study was performed at one of the largest ERCP centers in the country, with a staff that has extensive experience in duodenoscope reprocessing. In addition, the authors and center have a history of prior efforts involving assessing and developing quality improvement measures regarding duodenoscope reprocessing. These conditions may have led to a more robust and more carefully monitored manual cleaning of duodenoscopes than may not occur at sites with lower volume or less experience. Also, in the DHLD group, the authors performed a “true” double HLD, meaning they repeated both the manual cleaning and the HLD steps, which may have further limited the potential for residual contamination or biofilm formation. Some prior studies have not included a second manual cleaning step in their DHLD protocol.
      • Snyder G.M.
      • Wright S.B.
      • Smithey A.
      • et al.
      Randomized comparison of 3 high-level disinfection and sterilization procedures for duodenoscopes.
      ,
      • Bartles R.L.
      • Leggett J.E.
      • Hove S.
      • et al.
      A randomized trial of single versus double high-level disinfection of duodenoscopes and linear echoendoscopes using standard automated reprocessing.
      Furthermore, although the authors sampled the duodenoscope tip and elevator recess during the culturing process, they did not sample the instrument channel.
      Although most residual bacterial contamination occurs in the region of the elevator, a significant portion may occur in the instrument channel.
      • Bartles R.L.
      • Leggett J.E.
      • Hove S.
      • et al.
      A randomized trial of single versus double high-level disinfection of duodenoscopes and linear echoendoscopes using standard automated reprocessing.
      As a result, bacterial growth in this region could have been missed. In this study, it appears culturing was performed in the same manner as in this group’s prior study, where cultures were collected by “1 of 5 trained staff”
      • Rex D.K.
      • Sieber M.
      • Lehman G.A.
      • et al.
      A double-reprocessing high-level disinfection protocol does not eliminate positive cultures from the elevators of duodenoscopes.
      rather than with 2 staff members, as ideally recommended by the Centers for Disease Control and Prevention. The use of 1 staff member rather than 2 could have led to inadequate sampling, thus contributing to a lower contamination rate. It should be noted, however, that a 1-person culturing protocol could also have conversely led to higher culture positivity rates resulting from an increased risk of environmental contamination. Finally, the authors performed single HLD after each culturing process, further augmenting device reprocessing before obtaining the next culture, potentially lowering future culture positivity rates.
      When these factors are considered, the low bacterial contamination rates observed by use of each method in this study could be interpreted in either of 2 ways. First, if we view the glass as “half full,” this could be seen as a marker of superior reprocessing with both of these enhanced techniques compared with standard single HLD and a step closer in getting us to eliminating duodenoscope-transmitted infections. Alternatively, these results could reflect improved training and adherence to manual cleaning and also to additional quality improvements surrounding standard HLD reprocessing and storage, rather than the enhanced reprocessing techniques themselves. At present, it appears even the most thorough manual cleaning protocol and enhanced HLD reprocessing are unlikely to eradicate all potential pathogens. This “half empty” interpretation indicates that residual bacterial contamination is inevitable, regardless of reprocessing technique.
      In this study, the authors did not compare LCS or DHLD with single HLD; therefore, we cannot directly determine which interpretation is accurate. The authors reasoned that including a single HLD control would be substandard because it is not among the FDA’s supplemental measures. However, assessing reprocessing adequacy among these options by surveillance culturing, which is a listed enhanced reprocessing measure, would theoretically have enabled the inclusion of a control group undergoing single HLD, in our opinion.
      Safety Communications >Supplemental Measures to Enhance Duodenoscope Reprocessing: FDA Safety Communication.
      This point is especially important because recent evidence suggests that single HLD, in optimal conditions, may yield similarly favorable results. A study by Ross et al
      • Ross A.S.
      • Baliga C.
      • Verma P.
      • et al.
      A quarantine process for the resolution of duodenoscope-associated transmission of multidrug-resistant Escherichia coli.
      found a 1.9% contamination rate with high-concern organisms after single HLD.
      A more recent study from the same center by Higa et al
      • Higa J.T.
      • Choe J.
      • Tombs D.
      • et al.
      Optimizing duodenoscope reprocessing: rigorous assessment of a culture and quarantine protocol.
      found a 0.7% contamination rate after single HLD and noted that after culprit duodenoscopes were withdrawn and new manual cleaning protocols were implemented, the contamination rate with high-concern organisms in the last year of the study period was 0.3%. If we use these data as a historical single HLD control, the 0.5% contamination rate with high-concern organisms observed in this study
      • Gromski M.A.
      • Sieber M.S.
      • Sherman S.
      • et al.
      Double high-level disinfection versus liquid chemical sterilization for reprocessing of duodenoscopes used for ERCP: a prospective, randomized study.
      may not indicate a clear advantage of supplemental reprocessing. Instead, the favorable results may indicate that our longitudinal efforts in optimizing standard duodenoscope reprocessing by single HLD may be achieving dividends.
      Another significant challenge in interpreting these findings is the nature of the outcome we are trying to prevent. Fortunately, a clinically significant duodenoscope-transmitted infection is an extremely rare event and is therefore not a practical study outcome. Although surveillance culturing is a logical surrogate marker, it has several limitations. There has been wide variability in the culture techniques used among studies, including variations in experience among staff, different areas of the device that are sampled, techniques used (ie, brush, flush, or swab), and number of staff used to collect cultures. Therefore, a low culture positivity rate, such as that observed in this study, may not be the most accurate reflection of true infection risk. Other surrogate markers, including adenosine triphosphate testing, produce rapid results but are limited by their relation to clinical infections and also to their poor correlation with culture results.
      • Olafsdottir L.B.
      • Wright S.B.
      • Smithey A.
      • et al.
      Adenosine triphosphate quantification correlates poorly with microbial contamination of duodenoscopes.
      Without a reliable surrogate marker for clinical infections, it becomes difficult to determine when real progress is being made in preventing future duodenoscope outbreaks and in comparing reprocessing techniques.
      Although quality improvements to our current HLD reprocessing protocols can produce a low culture positivity rate, the persistent potential for human error likely means that even the best manual cleaning protocol may never truly allow us to eradicate all potential pathogens. Despite this challenge, future studies should continue to focus on how our reprocessing methods can bring us as close as humanly possible to this lofty goal. We recommend future prospective, randomized multicenter studies and postmarket surveillance studies done in real-world settings that will allow us to examine the impact of enhanced duodenoscope reprocessing with greater power and generalizability. Beyond enhanced reprocessing, newer modalities, including novel low-temperature sterilization options and changes in duodenoscope design such as detachable distal tips and/or elevators, should also be similarly assessed. As we have discussed, a challenge of all of these studies will be the selection of an appropriate primary outcome that can be easily obtained and reproduced and that will have a clear relationship with the potential for clinically evident infectious outbreaks. Without such a surrogate marker, which we believe is a key priority for the field, we will likely run into the same challenges interpreting future studies as we have with the work done to date in this field.
      In the future, the expenses associated with performing ERCP will almost certainly increase. Ongoing efforts to reduce and eventually eliminate the risk of infection transmission by duodenoscopes will have inevitable cost increases associated with new reprocessing equipment; new duodenoscope designs, including single-use devices; increased labor costs, performance of tests to validate adequate reprocessing, and/or changes in staff training. Moving forward, it will be critical for institutions to evaluate the cost/benefit ratio of different measures before overhauling their current reprocessing infrastructure. To this end, the authors should be commended for adding to the limited current literature of well-designed, prospective, randomized trials comparing enhanced HLD reprocessing measures.
      The lack of superiority of LCS over DHLD indicates that the clinical benefit of LCS may not be worth the costs associated with replacing existing HLD reprocessors with these devices. As we continue to make advances in reprocessing we must continue to carefully weigh the benefit of various advances with their associated costs. Given the recent development of single-use duodenoscopes, the costs and risk reductions associated with enhanced or novel alternative reprocessing pathways will need to be carefully weighed against single-use options. Assuming that single-use options can be shown to provide a comparable performance and safety profile to those of existing reusable devices, if the risk of duodenoscope-transmitted infections cannot be significantly diminished or eliminated with novel reprocessing methods, single-use devices may become a reasonable option. Albeit expensive, these devices do eliminate all potential for device transmission of infections and are appealing to patients. Future comparative studies such as this one will better establish a hierarchy of the cost-effectiveness of various new reprocessing technologies and better inform healthcare facilities and physicians in determining the most viable path forward in achieving and maximizing patient safety for ERCP procedures.

      Disclosure

      Dr Muthusamy is a consultant for and recipient of research support from Medtronic and Boston Scientific, a consultant to Interpace Diagnostics and Medivators, a stockholder in Capsovision, and the recipient of honoraria from Torax Medical/Ethicon. The other author disclosed no financial relationships.

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