Endoscope drying and its pitfalls

Drying of Soft Colloidal Films

Thin films made of deformable micro- and nano-units, such as biological membranes, polymer interfaces, and particle-laden liquid surfaces, exhibit a complex behavior during drying, with consequences for various applications like wound healing, coating technologies, and additive manufacturing. Studying the drying dynamics and structural changes of soft colloidal films thus holds the potential to yield valuable insights to achieve improvements for applications. In this study, interfacial monolayers of core-shell (CS) microgels with varying degrees of softness are employed as model systems and to investigate their drying behavior on differently modified solid substrates (hydrophobic vs hydrophilic). By leveraging video microscopy, particle tracking, and thin film interference, this study shed light on the interplay between microgel adhesion to solid surfaces and the immersion capillary forces that arise in the thin liquid film. It is discovered that a dried replica of the interfacial microstructure can be more accurately achieved on a hydrophobic substrate relative to a hydrophilic one, particularly when employing softer colloids as opposed to harder counterparts. These observations are qualitatively supported by experiments with a thin film pressure balance which allows mimicking and controlling the drying process and by computer simulations with coarse-grained models.

Effect of simethicone on the bactericidal efficacy of a high-level disinfectant

Introduction. Simethicone is an over-the-counter product that is frequently used by clinicians during endoscopic procedures to reduce foaming and improve visualization. Published studies have found simethicone residue on endoscopes after cleaning and disinfecting the devices as per the manufacturer's instructions. Some literature suggests that simethicone residue may reduce disinfection efficacy and increase the risk of patient infections.Gap Statement. However, there appears to be a lack of direct evidence in the literature to either disprove this or correlate simethicone presence with an increased microbial risk.Aim: Research was conducted to evaluate the in vitro impact of simethicone on disinfection efficacy.Methodology. Bacteria were grown in a microtitre plate assay in the presence of a range of simethicone concentrations and then treated with a disinfectant. Bacterial growth was assessed by spotting each microtitre well onto an agar plate.Results. The results demonstrated that, under the conditions tested, simethicone did not reduce the efficacy of Cidex ortho-phthalaldehyde disinfectant, which demonstrated at least a 6-log unit reduction in bacterial viability. Additional experiments showed that direct exposure to 66 mg ml-1 of simethicone reduced bacterial viability.Conclusion. These results indicate that simethicone may not reduce the bactericidal efficacy of disinfectant during reprocessing, under certain conditions.

Endoscope channel drying, storage, and conditions after reprocessing: How safe are they in clinical practice?

INTRODUCTION AND AIMS

Adequate drying and proper storage of flexible endoscopes are essential for maintaining quality in their reprocessing. The aim of the present study was to evaluate the drying stages, storage, and channel conditions of endoscopes through borescope inspection.

MATERIAL AND METHODS

The personnel responsible for endoscope reprocessing were interviewed. Storage conditions at 10 endoscopy facilities were inspected and an internal examination of the channels and ports of the stored equipment was carried out, utilizing a borescope. A total of 74 stored endoscope channels were evaluated.

RESULTS

Only 10% of the facilities inspected utilized transport cases for storage and only 10% had rooms exclusively used for storage. Sixty percent of the facilities did not perform any shelf-life control. All the channels evaluated were scratched and fluids were present on 69% of them.

CONCLUSIONS

Endoscope reprocessing can be improved through the implementation of drying and storage control and validation tools, as well as the use of borescopes and periodic clinical audits.

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.

Alcohol flush does not aid in endoscope channel drying but may serve as an adjunctive microbiocidal measure: A new take on an old assumption

BACKGROUND

Alcohol is perceived to aid flexible endoscope channel drying, however we previously showed alcohol increased the time required to dry some channels with forced air versus water alone. Yet, alcohol may prevent microorganism outgrowth during storage. Drying endoscope channels has been shown to prevent outgrowth, but it is unknown if incomplete drying (<10 µL remaining) provides similar protection.

METHODS

Endoscope channel test articles were used to determine the efficacy of 70%-30% alcohol flush for prevention of Pseudomonas aeruginosa outgrowth and drying efficiency. For non-alcohol flushed channels, the impact of forced air drying on outgrowth of P. aeruginosa was determined.

RESULTS

Alcohol flush (70%-30%) prevented outgrowth with little to no recovery of P. aeruginosa during ambient storage. 70% alcohol increased channel drying time by 1.5 or 3-fold compared to 50% alcohol or water, respectively. Forced air drying of non-alcohol flushed channels greatly reduced the initial contamination level and prevented outgrowth. Incomplete drying of contaminated channels was akin to no application of forced air. Applying forced air for more time than necessary to remove residual liquid did not completely eliminate the low level recovery of P. aeruginosa.

CONCLUSIONS

Flushing with reduced concentrations of alcohol may provide a strategy to prevent microbial outgrowth while reducing drying time.

Evaluation of cold atmospheric plasma for the decontamination of flexible endoscopes

BACKGROUND

Despite adherence to standard protocols, residues including live microorganisms may remain on the various surfaces of reprocessed flexible endoscopes. Prions are infectious proteins notoriously difficult to eliminate.

AIM

We tested the potential of cold atmospheric plasma (CAP) for the decontamination of flexible endoscope various surfaces, measuring total proteins and prion-residual infectivity as an indicator of efficacy.

METHODS

New PTFE endoscope channels and metal test surfaces spiked with test soil or prion-infected tissues were treated using different CAP-generating prototypes. Surfaces were then examined for the presence of residues using very sensitive fluorescence epi-microscopy. Prion residual infectivity was determined using the wire implant animal model and a new, more sensitive cell infectivity assay.

FINDINGS

A CAP jet applied perpendicularly at close range on flat test surfaces removed soil within 3 minutes but left microscopic residues and failed to eliminate prion infectivity according to the wire implant animal assay. The longitudinal gas flow from CAP prototypes developed for the treatment of long channels led to the displacement and sedimentation of residual soil towards the distal end, when applied alone. Observations of the plasma inside glass tubes showed temporal and spatial heterogeneity within a limited range. After standard enzymatic manual pre-wash, "CAP-activated" gas effluents prevented prion transmission from treated endoscope channels according to our prion infectivity cell assay.

CONCLUSION

CAP shows promising results as a final step for surgical surfaces decontamination. Optimising CAP delivery could further enhance CAP efficacy, offering a safe, chemical-free alternative for the reprocessing of all luminal flexible endoscope surfaces.

A Single-Blind Study Testing the Preparation Accuracy of Bedside Precleaning Solutions Used for Flexible Endoscopes

Endoscopy-related pathogen transmission may occur if microorganisms are spread from patient to patient by contaminated equipment. Effective and safe endoscope reprocessing includes bedside precleaning, mechanical cleaning, high-level disinfection, storage, and drying. The aim of this research study was to observe and report on the variation in practice regarding the use of detergent for bedside precleaning of flexible gastrointestinal endoscopes. Endoscopy nurses working in the endoscopy unit at the Princess Alexandra Hospital, Australia, prepared four samples of detergent solution as per normal routine. Twenty-nine nurses participated providing in total 116 samples. There was a significant variation in detergent concentration. The detergent concentration variated between 2.00 and 288.20 ml/L ( M = 34.55, SD = 39.21). Two samples revealed lower concentrations than required. More than 25% of the samples contained at least a 10 times higher concentration than required (>40 ml/L). Current practice of bedside precleaning of gastrointestinal endoscopes was not deemed safe or cost-effective as it did not guarantee an adequate concentration of detergent. More precise methods to establish the required concentration of the bedside precleaning solution were introduced to improve practice.

How effective are the alcohol flush and drying cycles of automated endoscope reprocessors? Stripped endoscope model

BACKGROUND

Effective drying of the internal channels of endoscopes is essential to prevent the growth of water-borne pathogens and to assure adequate sterilization with vaporized hydrogen peroxide or ethylene oxide. The aim of this study was to evaluate the dryness of endoscopes after a routine disinfection process in an automated endoscope reprocessor.

METHODS

Stripped endoscopes (SE) that allow for visual inspection of the inside channels were reprocessed per protocol in a large urban medical center, with a 3-minute or 10-minute air flush following reprocessing. SE was hung and observed for any water within the channels after reprocessing and after a week of ambient storage. Ready-for-use endoscopes were also randomly spot-checked for moisture visually and with moisture detection paper.

RESULTS

All SE were grossly wet after HLD with a 3-minute air flush, despite alcohol flush and drying cycle. The 10-minute air flush was effective at drying the biopsy/suction channel, but not the air/water channels. Hanging had limited effect, being most effective in the biopsy/suction channels. Of the 77 ready-for-use respiratory and gastrointestinal endoscopes assessed, 37 (48.1%) showed evidence of retained moisture.

CONCLUSIONS

Air flush cycles commonly used in the final steps of automated endoscope reprocessing may not adequately dry endoscope channels, particularly the narrower diameter air/water channels. An extended 10-minute air flush appears effective at drying the larger biopsy/suction channel, but has limited effect on the air/water channels.

Investigation of the Internal Conditions of 213 Reprocessed Endoscopic Channels

BACKGROUND AND AIMS

Studies have indicated that endoscope reprocessing failure might be attributed to internal damage or residual liquid in endoscopes. However, large-sample survey data on the internal conditions of endoscopic channels after reprocessing are lacking. This study used a borescope to investigate the internal cleanliness and damage of 213 endoscopic biopsy channels after reprocessing at the endoscopy center of the First Affiliated Hospital of Nanchang University, provided in theoretical basis for the efficacy of endoscope reprocessing and maintenance.

METHODS

A borescope was used to observe and analyze the inside of the endoscopic biopsy channel of 213 reprocessed endoscopes (in accordance with the Chinese health industry standard "Regulation for cleaning and disinfection technique of flexible endoscope (WS 507-2016). Each endoscope was observed for at least 10 minutes, and the results were recorded and evaluated by 5 researchers independently.

RESULTS

In all, 2504 images and 109 videos were recorded, and abnormal findings were classified into 10 categories: scratches (91.5%, 195/213), scratches with adherent peel (46.0%, 98/213), discolored areas (49.3%, 105/213), transparent drops (28.2%, 60/213), milky drops (23.9%, 51/213), white particles (46.9%, 100/213), attached materials (37.6%, 80/213), wear on metal parts (41.3%, 88/213), rust (23.9%, 51/213), and black spots (35.7%, 76/213). Among scratches, those in Teflon from 0-10 cm at the apex of the biopsy channel outlet and in metal from 0-5 cm at the biopsy channel inlet accounted for 58.4% (114/195) and 96.4% (188/195), respectively.

CONCLUSIONS

Scratches were the most common form of damage in the endoscopic biopsy channels investigated and were related to the use of endoscopic accessories and cleaning brush materials. The incidence of other abnormalities gradually increased with the duration of use and began to increase significantly after 18 months. All abnormalities have a certain impact on the quality of endoscope reprocessing. We recommend that a borescope be used to check the inside of endoscopic biopsy channels regularly to determine the damage and cleaning conditions and that these channels be reprocessed, repaired, or replaced in a timely manner.

The utility of lighted magnification and borescopes for visual inspection of flexible endoscopes

INTRODUCTION

Infections have been linked to damaged or contaminated endoscopes with visible defects. Endoscope processing standards and guidelines state endoscopes should be visually inspected every time they are used. This study evaluated a new visual inspection program using magnification and borescopes in an endoscopy department that had not previously utilized these tools.

METHODS

Site personnel were given visual inspection tools and training before systematically examining fully processed endoscopes twice during a 2-month period. A risk assessment protocol was used to determine whether endoscopes required recleaning, repair, or other action. Findings were documented using log sheets, photographs, and videotapes.

RESULTS

Visible damage and residue or debris were observed in 100% of 25 endoscopes at both assessments, and 76% required repair. Defects at baseline included scratches (88%); channel shredding or peeling (80%); adhesive band disintegration (80%); residual soil or debris (white 84%; black 68%; brown 40%; yellow/green 36%; and orange/red 8%); retained fluid (52%); and dents (40%). Findings were similar at follow-up.

DISCUSSION/CONCLUSIONS

Visual inspection with magnification and borescopes identified actionable defects that could interfere with processing effectiveness in 100% of endoscopes. Infection preventionists have a critical role to play in supporting processing personnel now that standards, guidelines, and manufacturer instructions recommend enhanced visual inspection of every endoscope, every time.

Infection control in the bronchoscopy suite: effective reprocessing and disinfection of reusable bronchoscopes

PURPOSE OF REVIEW

With advancements in technology, flexible bronchoscopes have become thinner in diameter and in need of more thorough reprocessing to prevent infection transmission than ever before. Many experienced bronchoscopists are not aware of the critical steps involved in effective bronchoscope reprocessing and we hope to bridge this gap by describing this process in detail.

RECENT FINDINGS

Bronchoscope reprocessing includes several distinct steps (precleaning, leak testing, manual cleaning, visual inspection, terminal reprocessing, rinsing and drying). Each step is comprehensive and needs to be carried out systematically by trained personnel. Failure of any step can lead to serious downstream events such as outbreaks and pseudo-outbreaks. Some experts now recommend sterilization when feasible, although high-level disinfection remains the minimum standard. We also will review some literature on the utility of borescopes, automated endoscope reprocessors and disposable bronchoscopes.

SUMMARY

Our article will focus on the most recent recommendations for effective reprocessing and disinfection of reusable bronchoscopes.

Cleaning of in-hospital flexible endoscopes: Limitations and challenges

OBJECTIVE

to analyze the cleaning process of gastroscopes, colonoscopes and duodenoscopes in eight in-hospital health services.

METHOD

a cross-sectional study conducted with 22 endoscopes (eight gastroscopes, eight colonoscopes and six duodenoscopes), and microbiological analysis of 60 samples of air/water channels (all endoscopes) and elevator (duodenoscopes), in addition to protein testing. Descriptive statistics with calculation of frequencies and central tendency measures was used in data analysis.

RESULTS

the processing of 22 endoscopes was monitored with microbiological analysis for 60 channels. In the pre-cleaning procedure, in 82.3% (14/17) of the devices, gauze was used in cleaning the insertion tube. Incomplete immersion of the endoscope in detergent solution occurred in 72.3% (17/22) of the cases, and in 63.6% (14/22) there was no standardization of filling-in of the channels. Friction of the biopsy channel was not performed in 13.6% (3/22) of the devices. In the microbiological analysis, 25% (7/32) of the samples from the stored endoscopes were positive for microbial growth (from 2x101 to 9.5x104 CFU/mL), while after processing, contamination was 32% (9/28). Protein residues in the elevator channel were detected in 33% of duodenoscopes.

CONCLUSION

the results indicate important gaps in the stages of pre-cleaning and cleaning of endoscopes that, associated with presence of protein residues and growth of microorganisms of epidemiological importance, indicate limitations in safety of the processing procedures, which can compromise the disinfection processes and, consequently, their safe use among patients subjected to such tests.

Limpieza de endoscopios flexibles intrahospitalarios: limitaciones y desafíos

Resumen Objetivo: analizar el proceso de limpieza de gastroscopios, colonoscopios y duodenoscopios en ocho servicios de salud intrahospitalarios. Método: estudio transversal con 22 endoscopios, de los cuales ocho eran gastroscopios, ocho colonoscopios y seis duodenoscopios, y análisis microbiológico de 60 muestras de los canales de aire/agua (todos los endoscopios) y elevador (duodenoscopios), además de prueba de proteínas. En el análisis de los datos se utilizó estadística descriptiva, con cálculo de frecuencias y medidas de tendencia central. Resultados: el procesamiento de los 22 endoscopios fue monitoreado con el análisis microbiológico de 60 canales. En la prelimpieza, en el 82,3% (14/17) de los equipos se utilizó gasa para limpiar el tubo de inserción. En el 72,3% (17/22) de los casos la inmersión del endoscopio en solución detergente fue incompleta y en el 63,6% (14/22) no hubo estandarización del llenado de los canales. La fricción del canal de biopsia no se realizó en el 13,6% (3/22) de los equipos. En el análisis microbiológico, el 25% (7/32) de las muestras endoscópicas almacenadas dio positivo para crecimiento microbiano (2x101 a 9,5x104 UFC/ml), mientras que después del procesamiento, la contaminación fue del 32% (9/28). Se detectaron residuos de proteína en el canal elevador en el 33% de los duodenoscopios. Conclusión: los resultados indican que hay importantes lagunas en las etapas de prelimpieza y limpieza de los endoscopios que, junto con la presencia de residuos de proteínas y del crecimiento de microorganismos de importancia epidemiológica, indican limitaciones en la seguridad del procesamiento, que pueden comprometer los procesos de desinfección y, por ende, el uso seguro en los pacientes que se someten a esos procedimientos.

Limpeza de endoscópios flexíveis intra-hospitalares: limitações e desafios

Resumo Objetivo: analisar o processo de limpeza de gastroscópios, colonoscópios e duodenoscópios em oito serviços de saúde intra-hospitalar. Método: estudo transversal com 22 endoscópios, sendo oito gastroscópios, oito colonoscópios e seis duodenoscópios, e análise microbiológica de 60 amostras dos canais de ar/água (todos os endoscópios) e elevador (duodenoscópios), além de teste de proteína. Na análise dos dados, utilizou-se estatística descritiva, com cálculo de frequências e medidas de tendência central. Resultados: o processamento de 22 endoscópios foi acompanhado com análise microbiológica de 60 canais. Na pré-limpeza, em 82,3% (14/17) dos equipamentos, foi utilizada gaze na limpeza do tubo de inserção. A imersão incompleta do endoscópio em solução detergente ocorreu em 72,3% (17/22) dos casos, e em 63,6% (14/22) não havia padronização do preenchimento dos canais. A fricção do canal de biópsia não foi realizada em 13,6% (3/22) dos equipamentos. Na análise microbiológica, 25% (7/32) das amostras dos endoscópios armazenados foram positivas para crescimento microbiano (2x101 a 9,5x104 UFC/mL), enquanto após o processamento, a contaminação foi de 32% (9/28). Resíduos de proteína no canal do elevador foram detectados em 33% dos duodenoscópios. Conclusão: os resultados apontam lacunas importantes nas etapas de pré-limpeza e limpeza dos endoscópios que, associadas à presença de resíduos de proteína e ao crescimento de microrganismo de importância epidemiológica, sinalizam limitações na segurança do processamento, que podem comprometer os processos de desinfecção e consequentemente seu uso seguro entre pacientes submetidos a tais exames.

A narrative review on current duodenoscope reprocessing techniques and novel developments

Duodenoscopy-associated infections occur worldwide despite strict adherence to reprocessing standards. The exact scope of the problem remains unknown because a standardized sampling protocol and uniform sampling techniques are lacking. The currently available multi-society protocol for microbial culturing by the Centers for Disease Control and Prevention, the United States Food and Drug Administration (FDA) and the American Society for Microbiology, published in 2018 is too laborious for broad clinical implementation. A more practical sampling protocol would result in increased accessibility and widespread implementation. This will aid to reduce the prevalence of duodenoscope contamination. To reduce the risk of duodenoscopy-associated pathogen transmission the FDA advised four supplemental reprocessing measures. These measures include double high-level disinfection, microbiological culturing and quarantine, ethylene oxide gas sterilization and liquid chemical sterilization. When the supplemental measures were advised in 2015 data evaluating their efficacy were sparse. Over the past five years data regarding the supplemental measures have become available that place the efficacy of the supplemental measures into context. As expected the advised supplemental measures have resulted in increased costs and reprocessing time. Unfortunately, it has also become clear that the efficacy of the supplemental measures falls short and that duodenoscope contamination remains a problem. There is a lot of research into new reprocessing methods and technical applications trying to solve the problem of duodenoscope contamination. Several promising developments such as single-use duodenoscopes, electrolyzed acidic water, and vaporized hydrogen peroxide plasma are already applied in a clinical setting.

Sans Standardization: Effective Endoscope Reprocessing

Bronchoscopy is a commonly performed procedure within thoracic and critical care medicine. Modern bronchoscopes are technologically advanced tools made of fragile electronic components. Their design is catered to allow maximum maneuverability within the semi-rigid tracheobronchial tree. Effective cleaning and reprocessing of these tools can be a challenge. Although highly functional, the design poses several challenges when it comes to reprocessing. It is a very important step, and lapses in the procedure have been tied to nosocomial infections. The process lacks universal standardization; several organizations have developed their own recommendations. Data have shown that key stakeholders are not fully versed in the essentials of endoscope reprocessing. A significant knowledge gap exists between those performing bronchoscopy and those who are stewards of effective endoscope reprocessing. To service as a resource for bronchoscopists, this study summarizes the steps of effective reprocessing, details the important elements within a health-care facility that houses this process, and reviews some of the current data regarding the use of disposable endoscopes.

Biofilm accumulation in new flexible gastroscope channels in clinical use

OBJECTIVE

Assess the accumulation of protein and biofilm on the inner surfaces of new flexible gastroscope (FG) channels after 30 and 60 days of patient use and full reprocessing.

DESIGN

Clinical use study of biofilm accumulation in FG channels.

SETTING

Endoscopy service of a public hospital.

METHODS

First, we tested an FG in clinical use before the implementation of a revised reprocessing protocol (phase 1 baseline; n = 1). After replacement of the channels by new ones and the implementation of the protocol, 3 FGs were tested after 30 days of clinical use (phase 2; n = 3) and 3 FGs were tested after 60 days of clinical use (phase 3; n = 3), and the same FGs were tested in phase 2 and 3. Their biopsy, air, water, and air/water junction channels were removed and subjected to protein testing (n = 21), bacteriological culture (n = 21), and scanning electron microscopy (SEM) (n = 28). Air-water junction channels fragments were subjected to SEM only.

RESULTS

For the FGs, the average number of uses and reprocessing cycles was 60 times. Extensive biofilm was detected in air, water, and air-water junction channels (n = 18 of 28). All channels (28 of 28) showed residual matter, and structural damage was identified in most of them (20 of 28). Residual protein was detected in the air and water channels of all FG evaluated (phases 1-3), except for 1 air channel from phase 2. Bacteria were recovered from 8 of 21 channels, most air or water channels.

CONCLUSIONS

The short time before damage and biofilm accumulation in the channels was evident and suggests that improving the endoscope design is necessary. Better reprocessing methods and channel maintenance are needed.

Efficacy of flexible endoscope drying using novel endoscope test articles that allow direct visualization of the internal channel systems

BACKGROUND

Thorough drying of flexible endoscope channels has been identified as an essential reprocessing step. Yet, instructions are not specific on how to dry endoscopes. There is lack of data supporting efficacy of current drying practices, due to limitations in determining channel dryness.

METHODS

Novel endoscope test articles were used to evaluate the effectiveness of alcohol flush and hanging in an ambient endoscope storage cabinet. Prepared test articles were hung in a storage cabinet for 5 days and visually inspected for residual liquid. The procedure for preoperative inspection of endoscopic systems was performed to determine the procedure's efficacy for removing residual liquid. Then, testing was performed to assess the impact of pressure, residual liquid type and route of air application on time to dry using compressed air.

RESULTS

Alcohol flush followed by hanging in an ambient storage cabinet was not effective for drying endoscope channels, and residual liquid was not completely removed after performing the steps of the preoperative inspection of endoscopic channels. The factors impacting effective compressed air drying were channel dependent. For some channels, alcohol increased the time to dry.

CONCLUSIONS

Endoscope drying is complex; borescope evaluation does not ensure a dry device.

The Effectiveness of Drying on Residual Droplets, Microorganisms, and Biofilms in Gastrointestinal Endoscope Reprocessing: A Systematic Review

BACKGROUND

Despite endoscope reprocessing, residual droplets remain in gastrointestinal endoscope working channels. Inadequate drying of gastrointestinal endoscope working channels may promote microbial reproduction and biofilm formation, increasing the risk of infection in patients. This review was designed to provide the current status of gastrointestinal endoscope drying, emphasize the importance of gastrointestinal endoscope drying, and evaluate the effectiveness of different drying methods of gastrointestinal endoscope in reducing residual droplets and microbial growth risk.

METHODS

A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting checklist. The PubMed, Web of Science, Medline, EMBASE, EBSCO, CNKI, CQVIP, and Wanfang Data databases were searched from 2010 to 2020 to identify eligible articles focused on methods of gastrointestinal endoscope drying and the status of endoscope drying. The following key points were analyzed: type of intervention, amount of residual droplets, major microbial types, and effectiveness of biofilm intervention. JBI quality assessment tool was used to determine bias risk for inclusion in the article.

RESULTS

This review included twelve articles. Two of the articles reported lack of drying of gastrointestinal endoscopes while the other ten reported residual droplets, microbial growth, and biofilm formation after different methods of drying. Four articles reported 0 to 4.55 residual droplets; four articles reported that the main microbial types were cocci and bacilli, most commonly Staphylococcus, Escherichia coli, Bacillus maltophilia, and Pseudomonas aeruginosa; and two reported that drying could effectively reduce biofilm regeneration. The type of intervention is as follows: automatic endoscopy reprocessor (AER), manual compressed air drying, and the Dri-Scope Aid for automatic drying and drying cabinet.

CONCLUSIONS

While endoscope reprocessing may not always be effective, an automatic endoscope reprocessor plus the Dri-Scope Aid with automatic drying over 10 min or storage in a drying cabinet for 72 h may be preferred.

Introduction to Transmission of Infection: Potential Agents Transmitted by Endoscopy

Pathogen contamination of endoscopes depends on pathogen factors, surface factors, and environmental conditions. The most common pathogens associated with transmission and infections associated with gastrointestinal endoscope contamination are Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa. Biofilm production together with disruption to device surfaces play an outsized role in the risk of contamination. Sampling schemes are limited by these factors, and further developments are needed to improve the accuracy of sampling.

Antifogging/Antibacterial Coatings Constructed by N-Hydroxyethylacrylamide and Quaternary Ammonium-Containing Copolymers

Endoscopic surgery has gained widespread applications in various clinical departments, and endoscope surfaces with antifogging and antibacterial properties are essential for elaborate procedures. In this work, novel antifogging/antibacterial coatings were developed from a cationic copolymer and a hydrophilic copolymer, polyhedral oligomeric silsesquioxane-poly(quaternary ammonium compound-co-2-aminoethyl methacrylate hydrochloride) [POSS-P(QAC-co-AEMA)] and poly(N-hydroxyethylacrylamide-co-glycidyl methacrylate) [P(HEAA-co-GMA)] via a facile and green blending method. Such transparent coatings showed excellent antifogging performance under both in vitro and in vivo fogging conditions, mainly attributed to the high water-absorbing capability of HEAA and QAC. Antibacterial assays proved that the blending coatings had a superior antibacterial property, which could be improved with the proportion of POSS-P(QAC-co-AEMA) because of the bactericidal efficiency of cationic QAC. Meanwhile, owing to the high hydratability of HEAA, the blending coatings exhibited a bacteria-repelling property. By simply tuning the blending ratio of POSS-P(QAC-co-AEMA) and P(HEAA-co-GMA), the comprehensive bacteria-killing and bacteria-repelling properties of the coatings were achieved. Moreover, after incubating with red blood cells, the prepared blending coatings presented a lower hemolytic rate of less than 5%. The findings provided a potential means for addressing the challenge of fogging and bacterial contamination occurring in endoscopic lenses and other medical devices.

Duodenoscope-associated infections: a review

Flexible digestive endoscopes are used for the management of various conditions with hundreds of thousands of therapeutic procedures performed worldwide each year. Duodenoscopes are indispensable tools for the delivery of minimally invasive vital care of numerous pancreaticobiliary disorders. Despite the fact that nosocomial infections after endoscopic retrograde cholangiopancreatography (ERCP) have always been among the most frequently cited postprocedural complications, recent emergence of duodenoscope-transmitted multiple drug-resistant bacterial infections has led to intense research and debate yet with no clearly delineated solution. Duodenoscope-transmitted nosocomial infections have become one of the most visible topics in the recent literature. Hundreds of high-impact articles have therefore been published in the last decade. This review article discusses how such infections were seen in the past and what is the current situation in both research and practice and thus tries to solve some of the unanswered questions for the future. With the persistence of nosocomial infections despite strict adherence to both manufacturer-issued reprocessing protocols and international guidelines and regulations, an urgent and proper microbiologically driven common action is needed for controlling such nosocomial worldwide threat.

Tumor Seeding During Colonoscopy as a Possible Cause for Metachronous Colorectal Cancer

BACKGROUND AND AIMS

In patients who have undergone surgery for colorectal cancer (CRC), 3% have recurrence of (metachronous) CRC. We investigated whether tumor seeding during colonoscopy (iatrogenic implantation of tumor cells in damaged mucosa) increases risk for metachronous CRC.

METHODS

In a proof of principle study, we collected data from the Dutch National Pathology Registry for patients with a diagnosis of CRC from 2013 through 2015, with a second diagnosis of CRC within 6 months to 3.5 years after surgery. We reviewed pathology reports to identify likely metachronous CRC (histologically proven adenocarcinoma located elsewhere in the colon or rectum from the surgical anastomosis). For 22 patients fulfilling the inclusion criteria, we ascribed the most likely etiology to tumor seeding when endoscopic manipulations, such as biopsies or polypectomy, occurred at the location where the metachronous tumor was subsequently detected, after endoscopic manipulation of the primary tumor. We collected clinical data from patients and compared molecular profiles of the primary and metachronous colorectal tumors using next-generation sequencing. We then examined the source of seeded tumor. We tested whether tumor cells stay behind in the working channel of the endoscope after biopsies of colorectal tumors, and whether these cells maintain viability in organoid cultures.

RESULTS

In total, tumor seeding was suspected as the most likely etiology of metachronous CRC in 5 patients. Tumor tissues were available from 3 patients. An identical molecular signature was observed in the primary and metachronous colorectal tumors from all 3 patients. In 5 control cases with a different etiology of metachronous CRC, the molecular signature of the primary and metachronous tumor were completely different. Based on review of 2147 patient records, we estimated the risk of tumor seeding during colonoscopy to be 0.3%-0.6%. We demonstrated that the working channel of the colonoscope becomes contaminated with viable tumor cells during biopsy collection. Subsequent instruments introduced through this working channel also became contaminated. These cells were shown to maintain their proliferative potential.

CONCLUSIONS

In an analysis of primary and secondary tumors from patients with metachronous CRC, we found that primary tumor cells might be seeded in a new location after biopsy of the primary tumor. Although our study does not eliminate other possibilities of transmission, our findings and experiments support the hypothesis that tumor seeding can occur during colonoscopy via the working channel of the endoscope. The possibility of iatrogenic seeding seems low. However, our findings compel awareness on this potentially preventable cause of metachronous CRC.

Endoscope reprocessing: Comparison of drying effectiveness and microbial levels with an automated drying and storage cabinet with forced filtered air and a standard storage cabinet

BACKGROUND

Automated drying may help prevent endoscopically transmitted infections. We aimed to assess the efficacy of an automated drying and storage cabinet compared to a standard storage cabinet in achieving endoscope dryness postreprocessing and in reducing the risk of microbial growth.

METHODS

Drying times of bronchoscopes, colonoscopes, and duodenoscopes using 2 drying platforms (an automated drying and storage cabinet vs a standard storage cabinet) were measured using cobalt chloride paper. Drying assessments occurred at: 30 minutes, 1 hour, 2 hours, 3 hours, and 24 hours. A simple linear regression analysis compared rates of microbial growth after inoculation with Pseudomonas aeruginosa following high-level disinfection at: 0, 3 hours, 12 hours, 24 hours, and 48 hours.

RESULTS

Using the automated drying and storage cabinet, internal channels were dry at 1 hour and external surfaces at 3 hours in all endoscopes. With the standard storage cabinet, there was residual internal fluid at 24 hours, whereas external surfaces were dry at 24 hours. For bronchoscopes, colonoscopes, and duodenoscopes, the standard cabinet allowed for an average rate of colony forming unit growth of 8.1 × 10⁶ per hour, 8.3 × 10⁶ per hour, and 7.0 × 10⁷ per hour, respectively; the automated cabinet resulted in colony forming unit growth at an average rate of -28.4 per hour (P = .02), -38.5 per hour (P = .01), and -200.2 per hour (P = .02), respectively.

CONCLUSIONS

An automated cabinet is advantageous for rapid drying of endoscope surfaces and in reducing the risk of microbial growth postreprocessing.

A Systematic Review of Disposable Sheath Use During Flexible Endoscopy

Flexible endoscopes are exposed to blood, mucus, and other secretions during procedures. Single-use sheaths are designed to prevent contact between contaminants and reusable endoscope components. This systematic review examined findings from 22 studies that assessed endoscopic sheath use during urologic, gastrointestinal, or respiratory procedures. The evidence showed that sheaths were durable and yielded faster endoscope turnover times because their reusable components did not require high-level disinfection or sterilization. After a brief learning period, health care providers successfully assembled and maneuvered sheathed endoscopes. Patients generally did not experience greater discomfort during procedures in which sheaths were used. Microbial cultures of sheathed endoscopes were negative or similar to unsheathed endoscopes. More research is needed to evaluate the potential effect of disposable sheaths on infection risks. The evidence suggests that sheaths are a viable option for reliably providing a barrier between endoscopes and patients without affecting the quality of endoscopic procedures.

Safely reprocessing duodenoscopes: current evidence and future directions

Highly publicised outbreaks of various infections related to the use of duodenoscopes have increased public awareness of the once arcane and largely ignored subject of endoscope reprocessing. Since 2015, national professional societies, multiple federal agencies, and even the US Senate have written reports and guidelines on duodenoscope reprocessing. However, their recommendations are sometimes contradictory and difficult to implement, and new research on the topic is published regularly which further complicates the situation. With this flood of new and sometimes contradictory information, clinicians can feel confused about how to assure the safety of their patients undergoing duodenosocopy. This Review summarises the most salient current research on duodenoscope-associated outbreaks and reprocessing, and aims to provide clinicians with practical information applicable to their practice.

Comparison of automated and manual drying in the elimination of residual endoscope working channel fluid after reprocessing (with video)

BACKGROUND AND AIMS

Residual fluid within endoscope working channels after reprocessing may promote growth of pathogens. Current reprocessing guidelines therefore recommend endoscope drying with administration of forced filtered air; however, the duration and modality of administered air are not specified. The new DriScope Aid device enables automated administration of filtered air at controlled pressure through all internal endoscope channels. We systematically compared, for the first time, the impact of manual drying and automated drying on retained working channel fluid and bioburden after reprocessing.

METHODS

We assessed for residual working channel fluid after reprocessing and/or drying by using the SteriCam borescope. Drying was performed either manually (forced filtered air) or was automated (DriScope Aid) for either 5 or 10 minutes. Adenosine triphosphate (ATP) bioluminescence testing was performed on working channel rinsates after drying, to evaluate for residual bioburden.

RESULTS

Significantly more fluid droplets were evident after manual drying (4.55 ± 6.14) than with automated device-facilitated drying for either 5 minutes (0.83 ± 1.29; P = .007) or 10 minutes (0 ± 0; P = .001). ATP bioluminescence values were higher for manual drying compared with automated drying at 48 hours (P = .001) and 72 hours (P = .014) after reprocessing.

CONCLUSIONS

We demonstrate significantly fewer water droplets and delayed ATP bioluminescence values within endoscope working channels after automated drying compared with manual drying. In particular, virtually no retained fluid was evident within endoscope working channels after automated drying for 10 minutes. These findings support recommendations for automation of as many reprocessing steps as possible. Automated drying may decrease the risk of transmission of infection related to endoscopy.

Simethicone is retained in endoscopes despite reprocessing: impact of its use on working channel fluid retention and adenosine triphosphate bioluminescence values (with video)

BACKGROUND AND AIMS

Studies from our group and others demonstrate residual fluid in 42% to 95% of endoscope working channels despite high-level disinfection and drying. Additionally, persistent simethicone has been reported in endoscope channels despite reprocessing.

METHODS

Endoscopy was performed by using water or varied simethicone concentrations (0.5%, 1%, 3%) for flushing. After high-level disinfection/drying, we inspected endoscope working channels for retained fluid by using the SteriCam borescope. Working channel rinsates were evaluated for adenosine triphosphate (ATP) bioluminescence. Fourier transform infrared spectroscopy was performed on fluid droplets gathered from a colonoscope in which low-concentration simethicone was used.

RESULTS

Use of medium/high concentrations of simethicone resulted in a higher mean number of fluid droplets (13.5/17.3 droplets, respectively) and ATP bioluminescence values (20.6/23 relative light units [RLUs], respectively) compared with that of procedures using only water (6.3 droplets/10.9 RLUs; P < .001). Two automated endoscope reprocessing cycles resulted in return of a fluid droplet and ATP bioluminescence values to ranges similar to that of procedures that used only water (P = .56). Low-concentration simethicone did not increase the mean residual fluid or ATP bioluminescence values compared with procedures that used only water (5.8 droplets/15.6 RLUs). Fourier transform infrared analysis revealed simethicone in the endoscope working channel after use of low-concentration simethicone.

CONCLUSIONS

Use of medium/high concentrations of simethicone is associated with retention of increased fluid droplets and higher ATP bioluminescence values in endoscope working channels, compared with endoscopes in which water or low concentration simethicone was used. However, simethicone is detectable in endoscopes despite reprocessing, even when it is utilized in low concentrations. Our data suggest that when simethicone is used, it should be used in the lowest concentration possible. Facilities may consider 2 automated endoscope reprocessor cycles for reprocessing of endoscopes when simethicone has been used.

Inspection of endoscope instrument channels after reprocessing using a prototype borescope

BACKGROUND AND AIMS

Visual inspection of the instrument channel has been proposed as a quality assurance step during endoscope reprocessing. However, the nature and severity of findings in a broad array of endoscopes (gastroscopes, colonoscopes, duodenoscopes, and echoendoscopes) after systemic implementation of an inspection protocol remain unknown. In addition, a study using borescope inspection in upper endoscopes and colonoscopes raised concerns about persistent simethicone residue despite full reprocessing.

METHODS

A pilot inspection study using a prototype borescope (SteriCam Inspection Scope; SteriView Inc, San Rafael, Calif) was performed on routinely used endoscopes after high-level disinfection, manual forced-air dry of the instrument channel, and overnight vertical storage. Video recordings 1.5 to 2 minutes in duration were reviewed for visible moisture, debris, discoloration, scratches, channel shredding (scratches that result in strips or filaments of the channel lining protruding into the lumen), and visible evidence of biofilm or simethicone residue.

RESULTS

A total of 97 inspections of 59 endoscopes were reviewed. The most common finding was scratches, seen in 51 devices (86%). Channel shredding was found in 35 devices (59%). Intrachannel debris was identified in 22 (23%) of the 97 inspections. No moisture was seen (0%) in the 74 inspections performed after forced-air dry and overnight vertical storage compared with moisture in 5 of 18 inspections (28%) performed after storage alone. No visual evidence of biofilm or simethicone residue was discovered despite its frequent use in our unit.

CONCLUSION

Internal defects of the instrument channel appear to occur frequently. Manual forced-air drying of the channel appears to be highly effective in eliminating moisture compared with overnight hang drying alone. Video inspection of the endoscope channel may be useful to audit reprocessing performance and to identify damaged endoscopes.

Residual moisture and waterborne pathogens inside flexible endoscopes: Evidence from a multisite study of endoscope drying effectiveness

BACKGROUND

Endoscopy-associated infection transmission is frequently linked to inadequate reprocessing. Residual organic material and moisture may foster biofilm development inside endoscopes. This study evaluated the effectiveness of endoscope drying and storage methods and assessed associations between retained moisture and contamination.

METHODS

Endoscope reprocessing, drying, and storage practices were assessed at 3 hospitals. Researchers performed visual examinations and tests to detect fluid and contamination on patient-ready endoscopes.

RESULTS

Fluid was detected in 22 of 45 (49%) endoscopes. Prevalence of moisture varied significantly by site (5%; 83%; 85%; P < .001). High adenosine triphosphate levels were found in 22% of endoscopes, and microbial growth was detected in 71% of endoscopes. Stenotrophomonas maltophilia, Citrobacter freundii, and Lecanicillium lecanii/Verticillium dahliae were found. Retained fluid was associated with significantly higher adenosine triphosphate levels (P < .01). Reprocessing and drying practices conformed with guidelines at 1 site and were substandard at 2 sites. Damaged endoscopes were in use at all sites.

CONCLUSIONS

Inadequate reprocessing and insufficient drying contributed to retained fluid and contamination found during this multisite study. More effective methods of endoscope reprocessing, drying, and maintenance are needed to prevent the retention of fluid, organic material, and bioburden that could cause patient illness or injury.