A prospective, multicenter, clinical study of duodenoscope contamination after reprocessing

Endoscope processing effectiveness: A reality check and call to action for infection preventionists and clinicians

BACKGROUND

Flexible endoscopes are heavily exposed to blood, mucus, and other secretions during procedures and may harbor billions of microbes before processing. Guidelines recommend thorough cleaning and sterilization or high-level disinfection (HLD) after each use.

METHODS

This review describes evidence on the effectiveness of HLD from a robust review of peer-reviewed journals, adverse events reports posted by the Food and Drug Administration, and other government reports published during 2019-2024.

RESULTS

Although HLD theoretically eliminates viruses, fungi, and bacteria (except a few resilient spores), numerous studies found it did not reliably eliminate microbes in real-world settings, and a large proportion of endoscopes harbored substantial bioburden and potential pathogens. Dozens of endoscopy-associated outbreaks have been reported in the past 5years, including several involving multidrug-resistant organisms. When contaminated endoscopes or endoscopy-associated infections were discovered, investigators commonly found that personnel were skipping essential steps or doing them improperly.

DISCUSSION

To reduce infection risk and enhance patient safety, infection preventionists, clinicians, sterile processing and departmental managers, and other leaders should review the evidence, perform risk assessments, and implement proactive strategies for quality improvement in their facilities.

Novel technology for automated cleaning of flexible endoscopes

Reprocessing of flexible endoscopes is a multi-stage system with many sequential stages. Errors in any one of the stages can result in microbial contamination that persists in patient ready endoscopes despite full reprocessing. One stage that is especially prone to errors is the manual cleaning of channels and exterior surfaces of flexible endoscopes. This editorial discusses the current factors in manual cleaning that lead to errors in cleaning adequacy. It also reviews novel technologies that provide improvements in cleaning of flexible endoscope channels.

Contamination of Disposable Distal Cap Duodenoscopes and Detachable Elevator Duodenoscopes After Reprocessing: A Randomized Trial

BACKGROUND AND AIM

To reduce bacterial contamination after reprocessing, various new designs of duodenoscopes have been developed to better expose the elevator complex for cleaning. We compared the rates of bacterial contamination and organic residue in disposable distal cap duodenoscopes and detachable elevator duodenoscopes after manual cleaning and high-level disinfection (HLD), as well as their cost-effectiveness.

METHODS

A total of 162 duodenoscopes were randomly assigned to either Group A (disposable distal caps; n = 81) or Group B (detachable elevator; n = 81). A total of 324 samples from the elevator were collected for culture following manual cleaning (n = 81 in each group) and HLD (n = 81 in each group), followed by the adenosine triphosphate (ATP) testing for organic residue.

RESULTS

After manual cleaning, there was no difference in bacterial contamination rates (8.6% vs. 8.6%; p = 1.00) and mean ATP levels (164.6 ± 257.5 vs. 158.1 ± 286.1 RLUs; p = 0.88) between Groups A and B. After HLD, no bacterial contamination was observed in either group and the mean ATP levels were very low with no significant difference between the two groups (30.1 ± 45.3 vs. 37.5 ± 51.9 RLUs; p = 0.68). The expense in reprocessing (excluding the scope cost) for Group A was lower (2099 USD) than Group B (3854 USD) in providing comparable scope cleanliness.

CONCLUSION

After manual cleaning, the bacterial contamination rate and organic residue levels in detachable elevator duodenoscopes and disposable distal caps duodenoscopes were comparable. No bacterial contamination was detected in either type of duodenoscope after reprocessing. Apart from the initial differences in scope cost, the disposable distal cap duodenoscope had lower cost on disposable items to have comparable disinfection result.

Efficacy of cleaning, disinfection, and sterilization modalities for addressing infectious drug-resistant fungi: a review

This is a timely and important review that focuses on the appropriateness of established cleaning, disinfection, and sterilization methods to safely and effectively address infectious fungal drug-resistant pathogens that can potentially contaminate reusable medical devices used in healthcare environment in order to mitigate the risk of patient infection. The release of the World Health Organization (WHO) fungal priority pathogen list (FPPL) in 2022 highlighted the public health crisis of antimicrobial resistance (AMR) in clinically relevant fungal species. Contamination of medical devices with drug-resistant fungal pathogens (including those on the FPPL) in healthcare is a rare event that is more likely to occur due to cross-transmission arising from lapses in hand hygiene practices. Established disinfection and sterilization methods decontaminate fungal pathogens on single-use and reusable medical devices; however, there are assumptions that reusable devices destined for semi-critical use are appropriately cleaned and do not harbour biofilms that may undermine the ability to effectively decontamination these type devices in healthcare. International standards dictate that manufacturer's instructions for use must provide appropriate guidance to healthcare facilities to meet safe reprocessing expectations that include addressing drug-resistant fungal pathogens. Increased environmental monitoring and vigilance surrounding fungal pathogens in healthcare is advised, including adherence to hand hygiene/aseptic practices and appropriate cleaning encompassing the simplification of reusable device features for 'ease-of-reach'. There are emereging opportunities to promote a more integrated multiactor hub approach to addressing these sophisticated challenges, including future use of artificial intelligence and machine learning for improved diagnostics, monitoring/surveillance (such as healthcare and wastewater-based epidemiology), sterility assurance, and device design. There is a knowledge gap surrounding the occurrence and potential persistence of drug-resistant fungal pathogens harboured in biofilms, particularly for ascertaining efficacy of high-level disinfection for semi-critical use devices.

Simulated-use evaluation of rapid ChannelCheck™ cleaning test for optimal detection of organic residues in flexible endoscope channels

BACKGROUND

The need to monitor manual cleaning of high-risk endoscopes is recommended or more so required by the current endoscope reprocessing guidelines. The objective of this study was to establish the optimal extraction volume for colonoscopes and bronchoscopes and demonstrate the extraction efficacy for the ChannelCheck™ rapid test.

METHODS

The test soil utilized as a positive control was ATS2015 containing 20% defibrinated bovine blood. The extraction from the instrument channel of a colonoscope and bronchoscope was evaluated to establish the optimal extraction volume and the extraction efficacy for protein, carbohydrate and haemoglobin.

RESULTS

Of the extraction volumes tested, 10 mL was optimal for both colonoscopes and bronchoscopes. The extraction efficacy was 91% for carbohydrate, 83.7% for haemoglobin and 82.4% for protein.

CONCLUSIONS

The limit of detection for these analytes by the ChannelCheck rapid test meet or exceed the established levels that correlate with adequate manual cleaning of flexible endoscopes.

Comparison of Sampling Methods for Detecting Protein in Gastrointestinal Endoscopes

Background: Persistent microbial contamination of flexible endoscopes has been linked to infections and outbreaks. Valid and reliable sampling methods are critical for monitoring processing effectiveness in flexible endoscopes. In this study, the effectiveness of protein extraction via turbulent fluid flow (TFF) sampling was compared with flush-only sampling in manually cleaned gastrointestinal endoscopes. Methods: A crossover study design, in which both sampling methods were used in alternating order during each endoscope encounter, was utilized to assess protein levels after colonoscopes and gastroscopes underwent manual cleaning. Endoscope channels were sampled with 20 mL sterile water using TFF and flush-only methods. Protein levels were quantified using a spectrophotometer. Results: Protein samples were collected during a total of 40 encounters with 20 unique endoscopes (19 colonoscopes and 21 gastroscopes) following procedural use. More effluent was captured following TFF (20-30 mL) compared with flush-only (19-21 mL) sampling. Zero samples had detectable protein after flush-only sampling, and nine samples (22.5%; two gastroscopes and seven colonoscopes) had detectable protein following TFF sampling (range 1-4 μg/mL). Of those, four exceeded the 2 μg/mL study threshold for recleaning after the first cleaning and three of four dropped to 2 μg/mL or less after recleaning. Conclusion: TFF sampling of the entire suction-biopsy channel allowed the detection of residual protein in nine gastrointestinal endoscopes, whereas no protein was detected in samples obtained by manually flushing the instrument channel. More research is needed to characterize the real-world utility of using the TFF system to verify whether soil and bioburden have been effectively removed during processing. Numerous studies have documented that a majority of fully processed, patient-ready endoscopes harbor microbes.1-8 Microbes found in endoscopes include high-concern organisms (e.g., multidrug-resistant microbes and pathogens) that have been linked to endoscopy-associated outbreaks.9-12 In these outbreaks, visible residual soil was discovered during the outbreak investigation. Current guidelines and standards note that effectively cleaning endoscopes is critical to the success of high-level disinfection (HLD) and sterilization.13,14 Several studies by Ofstead and colleagues6,15,16 have documented high protein levels on endoscopes. A study involving colonoscopes and gastroscopes detected protein on 100% of manually cleaned endoscopes (range 3-11 μg/mL).6 Other studies also found protein in 100% of manually cleaned bronchoscopes (range 2-30 μg/mL) and sterilized ureteroscopes (range 9-32 μg/mL).15,16 These contamination levels were higher than positive controls, which were dirty gastroscopes that had not been manually cleaned. Microbes were found on 12.5% to 60% of fully processed endoscopes, including potential pathogens such as Pseudomonas aeruginosa, Escherichia coli, and Micrococcus luteus.6,15,16 This reinforces the need to verify that endoscopes are clean prior to undergoing HLD or sterilization. Evidence shows that protein can persist through multiple rounds of cleaning.17,18 Despite efforts to clean the endoscope, harvesting samples from surfaces that remain contaminated with soil can be challenging because sampling commonly uses the same tools as cleaning (e.g., brushes or swabs and flushing). Residual soil or bioburden may also be encased in a biofilm matrix that has been hardened through exposure to harsh chemicals used during HLD and/or sterilization and repeated cycles of drying,19,20 thereby increasing the difficulty of capturing a sample. Hervé et al.21 noted that protein deposits in endoscopes were able to resist brushing and flushing, especially in the presence of wear and damage. Historically, flush-only ("flush") sampling was used,22,23 but this method often was limited to the instrument channel and captured lower yields compared with more robust methods.4,24,25 As the effectiveness of sampling affects the validity of results of tests for organic soil and microbial cultures, more robust sampling methods may be required.26 Guidance on sampling for microbial cultures provided by the Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) involves incorporating a brushing step and an additional flushing step ("flush-brush-flush") to dislodge and flush out microbes.27 This method has been found to be more effective than flush sampling,3,24 but brushes cannot access every endoscope channel and may leave behind bristles. Researchers have reported that the FDA/CDC sampling method is cumbersome, time consuming,28 and prone to contamination.7 Even when using recommended sampling methods, investigators have reported needing to rely on external experts and destructive sampling to effectively harvest samples that ultimately revealed the outbreak pathogen.10,11 This underscores the importance of robust sampling methods, both to avoid false negatives from failing to capture soil or bioburden that is present and to avoid false positives from environmental contamination.7,29 Given the challenges associated with current sampling techniques for organic soil testing and microbial cultures, this study was conducted to evaluate a method that could potentially improve sample validity and reduce the influence of human factors on sampling. The automated turbulent fluid flow (TFF) system pumps a mixture of air and water through the suction and instrument channels from the suction connector to the distal end and into a sterile collection cup that is sealed during sampling to maintain a closed system. The turbulent flow provides friction to endoscope interior surfaces without needing to use a brush.30 In this study, protein extraction via TFF sampling was compared with flush sampling in manually cleaned gastrointestinal endoscopes.

Fluid retention in endoscopes: A real-world study on drying effectiveness

BACKGROUND

Outbreaks linked to inadequate endoscope drying have infected numerous patients, and current standards and guidelines recommend at least 10 minutes of forced air for drying channels. This study evaluated a new forced-air drying system (FADS) for endoscopes.

METHODS

Drying was assessed using droplet detection cards; visual inspection of air/water connectors, suction connectors, and distal ends; and borescope examinations of endoscope interiors. Assessments were performed after automated endoscope reprocessor (AER) alcohol flush and air purge cycles and after 10-minute FADS cycles.

RESULTS

Researchers evaluated drying during encounters with 22 gastroscopes and 20 colonoscopes. After default AER alcohol and air purge cycles, 100% (42/42) of endoscopes were still wet. Substantial fluid emerged from distal ends during the first 15 seconds of the FADS cycle, and droplets also emerged from air/water and suction connectors. Following FADS cycle completion, 100% (42/42) were dry, with no retained fluid detected by any of the assessment methods.

CONCLUSIONS

Multiple endoscope ports and channels remained wet after AER cycles intended to aid in drying but were dry after the FADS cycle. This study reinforced the need to evaluate the effectiveness of current drying practices and illustrated the use of practical tools in a real-world setting.

Unveiling 8 years of duodenoscope contamination: insights from a retrospective analysis in a large tertiary care hospital

OBJECTIVE

Contaminated duodenoscopes caused several hospital outbreaks. Despite efforts to reduce contamination rates, 15% of patient-ready duodenoscopes are still contaminated with gastrointestinal microorganisms. This study aimed to provide an overview of duodenoscope contamination over time, identify risk factors and study the effects of implemented interventions.

DESIGN

Duodenoscope culture sets between March 2015 and June 2022 at a Dutch tertiary care centre were analysed. Contamination was defined as (1) the presence of microorganisms of oral or gastrointestinal origin (MGO) or (2) any other microorganism with ≥20 colony-forming units/20 mL (AM20). A logistic mixed effects model was used to identify risk factors and assess the effect of interventions, such as using duodenoscopes with disposable caps, replacing automated endoscope reprocessors (AER) and conducting audits in the endoscopy department.

RESULTS

A total of 404 culture sets were analysed. The yearly contamination rate with MGO showed great variation, ranging from 14.3% to 47.5%. Contamination with AM20 increased up to 94.7% by 2022. For both MGO and AM20, the biopsy and suction channels were the most frequently contaminated duodenoscope components. The studied interventions, including audits, AER replacement and implementation of duodenoscopes with disposable caps, did not show a clear association with contamination rates.

CONCLUSION

Duodenoscope contamination remains a significant problem, with high contamination rates despite several interventions. Reprocessing the biopsy and suction channels is especially challenging. Changes in the design of reusable duodenoscopes, such as enabling sterilisation or easily replaceable channels, are necessary to facilitate effective duodenoscope reprocessing and to eliminate the risk of duodenoscope-associated infections.

A proposed cleaning classification system for reusable medical devices to complement the Spaulding classification

A central tenet in infection prevention is application of the Spaulding classification system for the safe use of medical devices. Initially defined in the 1950s, this system defines devices and surfaces as being critical, semi-critical or non-critical depending on how they will be used on a patient. Different levels of antimicrobial treatment, defined as various levels of disinfection or sterilization, are deemed appropriate to reduce patient risk of infection. However, a focus on microbial inactivation is insufficient to address this concern, which has been particularly highlighted in routine healthcare facility practices, emphasizing the underappreciated importance of cleaning and achieving acceptable levels of cleanliness. A deeper understanding of microbiology has evolved since the 1950s, which has led to re-evaluation of the Spaulding classification along with a commensurate emphasis on achieving appropriate cleaning. Albeit underappreciated, cleaning has always been important as the presence of residual materials on surfaces can interfere with the efficacy of the antimicrobial process to inactivate micro-organisms, as well as other risks to patients including device damage, malfunction and biocompatibility concerns. Unfortunately, this continues to be relevant, as attested by reports in the literature on the occurrence of device-related infections and outbreaks due to failures in processing expectations. This reflects, in part, increasing sophistication in device features and reuse, along with commensurate manufacturer's instructions for use. Consequently, this constitutes the first description and recommendation of a new cleaning classification system to complement use of the traditional Spaulding definitions to help address these modern-day technical and patient risk challenges. This quantitative risk-based classification system highlights the challenge of efficient cleaning based on the complexity of device features present, as an isolated variable impacting cleaning. This cleaning classification can be used in combination with the Spaulding classification to improve communication of cleaning risk of a reusable medical device between manufacturers and healthcare facilities, and improve established cleaning practices. This new cleaning classification system will also inform future creation, design thinking and commensurate innovations for the sustainable safe reuse of important medical devices.

New Hydrogels Nanocomposites Based on Chitosan, 2-Formylphenylboronic Acid, and ZnO Nanoparticles as Promising Disinfectants for Duodenoscopes Reprocessing

New hydrogels nanocomposites, based on iminoboronate hydrogels and ZnO nanoparticles (ZnO-NPs), were obtained and characterised in order to develop a new class of disinfectants able to fight the nosocomial infections produced by duodenoscopes investigation procedures. The formation of the imine linkages between chitosan and the aldehyde was demonstrated using NMR and FTIR spectroscopy, while the supramolecular architecture of the developed systems was evaluated via wide-angle X-ray diffraction and polarised optical microscopy. The morphological characterisation of the systems via scanning electron microscopy revealed the highly porous structure of the materials, in which no ZnO agglomeration could be observed, indicating the very fine and homogenous encapsulation of the nanoparticles into the hydrogels. The newly synthetised hydrogels nanocomposites was proven to have synergistic antimicrobial properties, being very efficient as disinfectants against reference strains as: Enterococcus faecalis, Klebsiella pneumoniae, and Candida albicans.

Investigation of the efficacy of an innovative endoscope drying and storage method in a simulated ERCP setting

Background and study aims  Drying after cleaning and disinfection is essential in the reprocessing of endoscopes since microorganisms can grow and form biofilms on wet surfaces. In this experimental non-clinical study, we investigated the efficacy of a novel, fast-drying method when reprocessing duodenoscopes. Methods  During a series of 40 tests, three duodenoscopes were exposed to an artificial test soil containing supraphysiological loads of four types of gut microorganisms in a non-clinical ERCP simulation, followed by reprocessing and drying with the PlasmaTYPHOON. Cultures of the distal tip and working channel were acquired immediately after automated decontamination and after drying with the PlasmaTYPHOON. Cobalt chloride paper tests and borescope inspections were used to evaluate drying efficacy. Results  Contamination of the working channels dropped from 86.4 % post-decontamination to 33.6 % post-drying, with 94 % of the positive post-drying samples belonging to one duodenoscope. This duodenoscope showed persistent contamination with P. aeruginosa in the working channel. The other two duodenoscopes only showed low levels of P. aeruginosa in post-decontamination channel samples, but not after drying. Cobalt chloride paper tests and borescope inspections revealed good drying efficacy. Conclusions  Positive cultures for gut microorganisms were often found in wet endoscopes post-decontamination. The PlasmaTYPHOON is an effective fast-drying method capable of abolishing nearly all remaining microorganisms after decontamination provided no biofilm has developed, even when using a supraphysiological concentration of bacterial load. The clinical use of the PlasmaTYPHOON has the potential to reduce endoscope contamination, the use of wet contaminated endoscopes and therefore the risk of patient infection.

Microbiological surveillance post-reprocessing of flexible endoscopes used in digestive endoscopy: a national study

INTRODUCTION

Microbiological surveillance of endoscopes is a safety measure for verifying the quality of reprocessing procedures and identifying contaminated devices, but duodenoscope-related outbreaks are still reported.

AIM

To assess the effectiveness of duodenoscope reprocessing procedures in Italy.

METHODS

Between December 2019 and April 2020, data obtained from microbiological surveillance post-reprocessing in 15 Italian endoscopy units were collected. Sampling was carried out after reprocessing or during storage in a cabinet. In keeping with international guidelines and the Italian position paper, the micro-organisms were classified as high-concern organisms (HCOs) and low-concern organisms (LCOs).

FINDINGS

In total, 144 samples were collected from 51 duodenoscopes. Of these, 36.81% were contaminated: 22.92% were contaminated with HCOs and 13.89% were contaminated with LCOs [2.08% with an LCO load of 11-100 colony-forming units (CFU)/device and 0.69% with an LCO load of >100 CFU/device]. The contamination rate was 27.5% in samples collected after reprocessing, 40% in samples collected during storage in a cabinet that was compliant with EN 16442:2015 (C-I), and 100% in samples collected during storage in a cabinet that was not compliant with EN 16442:2015 (NC-I). The respective HCO rates were 15.00%, 27.27% and 66.67%. Correlation between LCO contamination and storage time was demonstrated (Spearman's rho=0.3701; P=0.0026). The Olympus duodenoscope TJFQ180V demonstrated the lowest rate of contamination (29.82%), although the contamination rate was 100% for duodenoscopes stored in an NC-I cabinet.

CONCLUSION

Microbiological surveillance, along with strict adherence to reprocessing protocols, may help to detect endoscope contamination at an early stage, and reduce the risk of duodenoscope-associated infections.