Endoscope storage time: assessment of microbial colonization up to 21 days after reprocessing

Storage of gastrointestinal endoscopes: when is the safe time for re-use?

ABSTRACT Objectives: to identify the safe storage time for the use of flexible gastrointestinal endoscopes after high-level disinfection, as well as the defining criteria for this time. Methods: an integrative literature review was carried out in the Virtual Health Library, PubMed, Scopus, and Web of Science, considering original articles published since 2000. Results: eleven articles were selected, whose storage times ranged from 1 to 56 days, with a predominance of one to seven days (73%). Several criteria were used to define this time, predominantly the premise of efficient processing (100%), use of alcohol flush (64%), use of drying cabinets (18%), among others. Conclusions: the criteria for determining the storage time did not show a consensus for clinical practice. Expanding the discussion of this theme with the definition of the minimum necessary conditions is of fundamental importance for the reduction of risks and safety of the procedure and the patient.

Duodenoscope-Acquired Infections: Risk Factors to Consider

In the wake of highly publicized duodenoscope-associated outbreaks caused by multidrug-resistant organisms (MDRO), a herculean effort was made to understand the conditions that led to these transmission events. Although there is now a clearer picture on how these outbreaks happened, there are still significant data gaps when it comes to understanding the rate of duodenoscope-acquired infections (DAIs), especially in nonoutbreak situations. Recent publications indicate that DAIs are still occurring and suggest that infection rates are higher than currently believed. Given this data gap, it is important to identify those patient populations that are most at risk of postprocedure infection, so that appropriate infection control measures may be implemented. Although those patients receiving antibiotic prophylaxis are most at risk for infection, there are additional risk factors that should be considered. For the purposes of this review, risk factors for infection were divided into three broad categories as follows: (1) those that increase patient susceptibility to infection, (2) those related to the endoscopic procedure, and (3) those factors that put reusable duodenoscope inventories at risk of contamination. Infection risk is a complex interaction between the immune status of the patient, the characteristics of the infectious agent (antibiotic sensitivity, virulence factors, and epidemiology), and the environment of care. Because of this complexity, any assessment of the risk of infection should be performed on a case-by-case basis. There is a dearth of information on infection risk for those patients undergoing endoscopic retrograde cholangiopancreatograpy (ERCP), especially in the context of the development and implementation of new device technology, and new endoscopic procedures that are increasing in complexity. This narrative review was developed using the Medical Subject Heading (MeSH) terms to perform an electronic search in PubMed with the goal of generating a summary of the patient, procedural, and duodenoscope-associated factors that increase the risk of infection in patients undergoing ERCP. This review provides practical information regarding the segmentation of ERCP patients by infection risk, so that endoscopists can make informed decisions about the risk benefits of using enhanced duodenoscope technologies in the care of their patients.

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.

Novel Algorithms for Reprocessing, Drying and Storing Endoscopes

After outbreaks of duodenoscope-transmitted infection with multidrug-resistant organisms, it has become clear that institutions must optimize their endoscope reprocessing programs. Standard endoscope reprocessing practices may not represent the ideal approach for preventing transmission of infection related to endoscopy. We discuss multiple approaches to enhance and optimize reprocessing, drying, and storage of standard duodenoscopes. The optimal enhanced duodenoscope reprocessing modality remains to be determined. Acknowledging the challenges and limitations in effectively reprocessing duodenoscopes, the FDA issued a safety communiqué recommending transitioning to either single use disposable duodenoscopes or duodenoscopes with innovative designs that allow more effective reprocessing.

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.

Turbulent fluid flow is a novel closed-system sample extraction method for flexible endoscope channels of various inner diameters

OVERVIEW

Effective sample extraction from endoscope channels is crucial for monitoring manual cleaning adequacy as well as for ensuring optimal sensitivity for culture after disinfection. The objective of this study was to compare the efficacy of Turbulent Fluid Flow (TFF) to Flush (F) or Flush-Brush-Flush (FBF) methods.

MATERIALS & METHODS

Pseudomonas aeruginosa and Enterococcus faecalis in artificial test soil-2015 (ATS2015) were used as bacterial markers while protein and carbohydrate were the organic markers for biofilm formed inside 3.2-mm and 1.37-mm polytetrafluoroethylene (PTFE) channels. TFF was generated using compressed air and sterile water to provide friction for sample extraction. Extraction for biofilm coated PTFE channels as well as for colonoscope channels perfused with ATS2015 containing 10⁸ CFU/mL P. aeruginosa, E. faecalis and Candida albicans was determined using TFF compared to FBF and F.

RESULTS

The extraction ratio for P. aeruginosa and E. faecalis from biofilm extracted by TFF compared to the positive control was significantly better than F for 1.37-mm channels (≥0.94 for both bacteria by TFF versus 0.69 to 0.72 by F for P. aeruginosa and E. faecalis, respectively) but not significantly different between TFF and FBF for 3.2-mm channels. F was also ineffective for extraction of protein and carbohydrate from 1.37-mm channels. Extraction efficacy by TFF from inoculated colonoscope channels was >98% for all test markers.

CONCLUSIONS

The novel TFF method for extraction of samples from colonoscope channels is a more effective method than the existing FBF and F methods.

Duodenoscope-Associated Infections: Update on an Emerging Problem

The duodenoscope is among the most complex medical instruments that undergo disinfection between patients. Transmission of infection by contaminated scopes has remained a challenge since its inception. Notable risk factors for pathogen transmission include non-adherence to disinfection guidelines, encouragement of biofilm deposition due to complex design and surface defects and contaminated automated endoscope reprocessors. The most common infections following endoscopy are endogenous infections involving the patient's own gut flora. Exogenous infections, on the other hand, are associated with contaminated scopes and can theoretically be prevented by effective reprocessing. Pseudomonas aeruginosa is currently the most common organism isolated from contaminated endoscopes. Of note, reports of multidrug-resistant duodenoscopy-associated outbreaks have surfaced recently, many of which occurred despite adequate reprocessing. The FDA and CDC currently recommend comprehensive cleaning followed with at least high-level disinfection for reprocessing of flexible GI endoscopes. Reports of duodenoscope-related outbreaks despite compliance with established guidelines have prompted professional and government bodies to revisit existing guidelines and offer supplementary recommendations for duodenoscope processing. For the purposes of this review, we identified reports of duodenoscope-associated infections from 2000 till date. For each outbreak, we noted the organisms isolated, the number of cases reported, any possible explanations of contamination, and the measures undertaken to end each outbreak. We have also attempted to present an overview of recent developments in this rapidly evolving field.

Endoscope drying and its pitfalls

Inadequate drying of endoscope channels is a possible cause of replication and survival of remaining pathogens during storage. The presence during storage of potentially contaminated water in endoscope channels may promote bacterial proliferation and biofilm formation. An incomplete drying procedure or lack of drying and not storing in a vertical position are the most usual problems identified during drying and endoscope storage. Inadequate drying and storage procedures, together with inadequate cleaning and disinfection, are the most important sources of endoscope contamination and post-endoscopic infection. Flexible endoscopes may be dried in automated endoscope reprocessors (AERs), manually, or in drying/storage cabinets. Flushing of the endoscope channels with 70-90% ethyl or isopropyl alcohol followed by forced air drying is recommended by several guidelines. Current guidelines recommend that flexible endoscopes are stored in a vertical position in a closed, ventilated cupboard. Drying and storage cabinets have a drying system that circulates and forces the dry filtered air through the endoscope channels. Endoscope reprocessing guidelines are inconsistent with one another or give no exact recommendations about drying and storage of flexible endoscopes. There is no conclusive evidence on the length of time endoscopes can be safely stored before requiring re-disinfection and before they pose a contamination risk. To minimize the risk of disease transmission and nosocomial infection, modification and revision of guidelines are recommended as required to be consistent with one another.

Duodenoscope hang time does not correlate with risk of bacterial contamination

BACKGROUND

Current professional guidelines recommend a maximum hang time for reprocessed duodenoscopes of 5-14 days. We sought to study the association between hang time and risk of duodenoscope contamination.

METHODS

We analyzed cultures of the elevator mechanism and working channel collected in a highly standardized fashion just before duodenoscope use. Hang time was calculated as the time from reprocessing to duodenoscope sampling. The relationship between hang time and duodenoscope contamination was estimated using a calculated correlation coefficient between hang time in days and degree of contamination on the elevator mechanism and working channel.

RESULTS

The 18 study duodenoscopes were cultured 531 times, including 465 (87.6%) in the analysis dataset. Hang time ranged from 0.07-39.93 days, including 34 (7.3%) with hang time ≥7.00 days. Twelve cultures (2.6%) demonstrated elevator mechanism and/or working channel contamination. The correlation coefficients for hang time and degree of duodenoscope contamination were very small and not statistically significant (-0.0090 [P = .85] for elevator mechanism and -0.0002 [P = 1.00] for working channel). Odds ratios for hang time (dichotomized at ≥7.00 days) and elevator mechanism and/or working channel contamination were not significant.

CONCLUSIONS

We did not find a significant association between hang time and risk of duodenoscope contamination. Future guidelines should consider a recommendation of no limit for hang time.

Guideline Implementation: Processing Flexible Endoscopes

The updated AORN "Guideline for processing flexible endoscopes" provides guidance to perioperative, endoscopy, and sterile processing personnel for processing all types of reusable flexible endoscopes and accessories in all procedural settings. This article focuses on key points of the guideline to help perioperative personnel safely and effectively process flexible endoscopes to prevent infection transmission. The key points address verification of manual cleaning, mechanical cleaning and processing, storage in a drying cabinet, determination of maximum storage time before reprocessing is needed, and considerations for implementing a microbiologic surveillance program. Perioperative RNs should review the complete guideline for additional information and for guidance when writing and updating policies and procedures.

Duodenoscopy related infection risk and duodenoscope cleaning and disinfection

With the development of minimally invasive techniques, duodenoscope, as an instrument for diagnosis and treatment of pancreaticobiliary diseases, has been gradually applied in clinical practice. Iatrogenic infection caused by duodenoscopy is a well-documented complication, which has gained extensive attention especially in duodenoscope cleaning and disinfecting. It has been postulated that the complexity in design of duodenoscope makes cleaning difficult and poses a risk for nosocomial infections. As such, it is of positive practical significance to analyze the factors that affect cleaning and disinfecting and to take effective measures to do them better, in order to prevent nosocomial infection. This paper briefly reviews the cleaning and sterilizing of duodenoscope and the risk of infection associated with duodenoscopy.

Association Between Storage Interval and Contamination of Reprocessed Flexible Endoscopes in a Pediatric Gastrointestinal Procedural Unit

OBJECTIVE

The maximum safe storage interval after endoscope reprocessing remains unknown. We assessed the association between storage interval and endoscope contamination to evaluate the need for scope reprocessing prior to use.

METHODS

We conducted a study in 2 phases. In phase 1, we cultured 9 gastrointestinal (GI) endoscopes that had been stored for at least 7 days since reprocessing. Each scope was cultured in 3 places: external surfaces of hand piece, insertion tube, and internal channels. In phase 2, after reprocessing these scopes, we hung and cultured them prospectively in a similar fashion at 1-, 2-, 4-, 6-, and 8-week intervals without patient use. We defined clinically relevant contamination as >100 colony-forming units per milliliter (CFU/mL).

RESULTS

In phase 1, median hang time was 69 days (range, 8–555 days). Considering the 27 total cultures, 3 of 27 GI endoscopes (11.1%) had positive cultures, all with nonpathogenic skin flora at ≤100 CFU/mL. Median hang time was not statistically different between scopes with positive and negative cultures (P=.82). In phase 2, 7 of 131 prospective cultures (5.3%) from 6 of 9 GI endoscopes at varying storage intervals were positive, all at ≤100 CFU/mL. At 56 days after reprocessing (the longest storage interval studied), 1 of 24 cultures (4.2%) was positive (100 CFU/mL ofBacillusspecies from external biopsy/suction ports).

CONCLUSIONS

No endoscopes demonstrated clinically relevant contamination at hang times ranging from 7 to 555 days, and most scopes remained uncontaminated up to 56 days after reprocessing. Our data suggest that properly cleaned and disinfected GI endoscopes could be stored safely for longer intervals than currently recommended.

Infect. Control Hosp. Epidemiol.2017;38:131–135

Infectious complications in gastrointestinal endoscopy and their prevention

Gastrointestinal endoscopes are medical devices that have been associated with outbreaks of health care-associated infections. Because of the severity and limited treatment options of infections caused by multidrug-resistant Enterobacteriaceae and Pseudomonas aeruginosa, considerable attention has been paid to detection and prevention of these post-endoscopic outbreaks. Endoscope reprocessing involves cleaning, high-level disinfection/sterilization followed by rinsing and drying before storage. Failure of the decontamination process implies the risk of settlement of biofilm producing species in endoscope channels. This review covers the infectious complications in gastrointestinal endoscopy and their prevention and highlights the problem of infection risk associated with different steps of endoscope reprocessing.

Endoscope Reprocessing: Update on Controversial Issues

Several issues concerning endoscope reprocessing remain unresolved based on currently available data. Thus, further studies are required to confirm standard practices including safe endoscope shelf life, proper frequency of replacement of some accessories including water bottles and connecting tubes, and microbiological surveillance testing of endoscopes after reprocessing. The efficacy and cost-effectiveness of newer technology that allows automated cleaning and disinfection is one such controversial issue. In addition, there are no guidelines on whether delayed reprocessing and extended soaking may harm endoscope integrity or increase the bioburden on the external or internal device surfaces. In this review, we discuss the unresolved and controversial issues regarding endoscope reprocessing.