Pitfalls in endoscope reprocessing: brushing of air and water channels is mandatory for high-level disinfection

NCCP-ICS joint consensus-based clinical practice guidelines on medical thoracoscopy

ABSTRACT

Medical Thoracoscopy (MT) is commonly performed by respiratory physicians for diagnostic as well as therapeutic purposes. The aim of the study was to provide evidence-based information regarding all aspects of MT, both as a diagnostic tool and therapeutic aid for pulmonologists across India. The consensus-based guidelines were formulated based on a multistep process using a set of 31 questions. A systematic search of published randomized controlled clinical trials, open labelled studies, case reports and guidelines from electronic databases, like PubMed, EmBase and Cochrane, was performed. The modified grade system was used (1, 2, 3 or usual practice point) to classify the quality of available evidence. Then, a multitude of factors were taken into account, such as volume of evidence, applicability and practicality for implementation to the target population and then strength of recommendation was finalized. MT helps to improve diagnosis and patient management, with reduced risk of post procedure complications. Trainees should perform at least 20 medical thoracoscopy procedures. The diagnostic yield of both rigid and semirigid techniques is comparable. Sterile-graded talc is the ideal agent for chemical pleurodesis. The consensus statement will help pulmonologists to adopt best evidence-based practices during MT for diagnostic and therapeutic purposes.

Development of Novel Balloon-Integrated Optical Catheter for Endoscopic and Circumferential Laser Application

The current study aims to demonstrate the feasibility of a novel balloon-integrated optical catheter (BIOC) to achieve endoscopic laser application for circumferential coagulation of a tubular tissue structure. Both optical and thermal numerical simulations were developed to predict the propagation of laser light and a spatio-temporal distribution of temperature in tissue. Ex vivo esophagus tissue was tested with 980 nm laser light at 30 W for 90 s for quantitative evaluations. In vivo porcine models were used to validate the performance of BIOC for circumferential and endoscopic laser coagulation of esophagus in terms of acute tissue responses post-irradiation. Optical simulations confirmed that a diffusing applicator was able to generate a circumferential light distribution in a tubular tissue structure. Both numerical and experimental results presented that the maximum temperature elevation occurred at 3-5 mm (muscle layer) below the mucosa surface after 90 s irradiation. In vivo tests confirmed the circumferential delivery of laser light to a deep muscle layer as well as no evidence of thermal damage to the esophageal mucosa. The proposed BIOC can be a feasible optical device to provide circumferential laser irradiation as well as endoscopic coagulation of tubular esophagus tissue for clinical applications.

High-level disinfection of gastrointestinal endoscope reprocessing

High level disinfection (HLD) of the gastrointestinal (GI) endoscope is not simply a slogan, but rather is a form of experimental monitoring-based medicine. By definition, GI endoscopy is a semicritical medical device. Hence, such medical devices require major quality assurance for disinfection. And because many of these items are temperature sensitive, low-temperature chemical methods, such as liquid chemical germicide, must be used rather than steam sterilization. In summarizing guidelines for infection prevention and control for GI endoscopy, there are three important steps that must be highlighted: manual washing, HLD with automated endoscope reprocessor, and drying. Strict adherence to current guidelines is required because compared to any other medical device, the GI endoscope is associated with more outbreaks linked to inadequate cleaning or disinfecting during HLD. Both experimental evaluation on the surveillance bacterial cultures and in-use clinical results have shown that, the monitoring of the stringent processes to prevent and control infection is an essential component of the broader strategy to ensure the delivery of safe endoscopy services, because endoscope reprocessing is a multistep procedure involving numerous factors that can interfere with its efficacy. Based on our years of experience in the surveillance of culture monitoring of endoscopic reprocessing, we aim in this study to carefully describe what details require attention in the GI endoscopy disinfection and to share our experience so that patients can be provided with high quality and safe medical practices. Quality management encompasses all aspects of pre- and post-procedural care including the efficiency of the endoscopy unit and reprocessing area, as well as the endoscopic procedure itself.

Results from a Large-Scale Epidemiologic Look-Back Investigation of Improperly Reprocessed Endoscopy Equipment

Objective.

To determine whether improper high-level disinfection practices during endoscopy procedures resulted in bloodborne viral infection transmission.

Design.

Retrospective cohort study.

Setting.

Four Veterans Affairs medical centers (VAMCs).

Patients.

Veterans who underwent colonoscopy and laryngoscopy (ear, nose, and throat [ENT]) procedures from 2003 to 2009.

Methods.

Patients were identified through electronic health record searches and serotested for human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV). Newly discovered case patients were linked to a potential source with known identical infection, whose procedure occurred no more than 1 day prior to the case patient's procedure. Viral genetic testing was performed for case/proximate pairs to determine relatedness.

Results.

Of 10,737 veterans who underwent endoscopy at 4 VAMCs, 9,879 patients agreed to viral testing. Of these, 90 patients were newly diagnosed with 1 or more viral bloodborne pathogens (BBPs). There were no case/proximate pairings found for patients with either HIV or HBV; 24 HCV case/proximate pairings were found, of which 7 case patients and 8 proximate patients had sufficient viral load for further genetic testing. Only 2 of these cases, both of whom underwent laryngoscopy, and their 4 proximates agreed to further testing. None of the 4 remaining proximate patients who underwent colonoscopy agreed to further testing. Mean genetic distance between the 2 case patients and 4 proximate patients ranged from 13.5% to 19.1%.

Conclusions.

Our investigation revealed that exposure to improperly reprocessed ENT endoscopes did not result in viral transmission in those patients who had viral genetic analysis performed. Any potential transmission of BBPs from colonoscopy remains unknown.

Results from a Large-Scale Epidemiologic Look-Back Investigation of Improperly Reprocessed Endoscopy Equipment

Objective.

To determine whether improper high-level disinfection practices during endoscopy procedures resulted in bloodborne viral infection transmission.

Design.

Retrospective cohort study.

Setting.

Four Veterans Affairs medical centers (VAMCs).

Patients.

Veterans who underwent colonoscopy and laryngoscopy (ear, nose, and throat [ENT]) procedures from 2003 to 2009.

Methods.

Patients were identified through electronic health record searches and serotested for human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV). Newly discovered case patients were linked to a potential source with known identical infection, whose procedure occurred no more than 1 day prior to the case patient's procedure. Viral genetic testing was performed for case/proximate pairs to determine relatedness.

Results.

Of 10,737 veterans who underwent endoscopy at 4 VAMCs, 9,879 patients agreed to viral testing. Of these, 90 patients were newly diagnosed with 1 or more viral bloodborne pathogens (BBPs). There were no case/proximate pairings found for patients with either HIV or HBV; 24 HCV case/proximate pairings were found, of which 7 case patients and 8 proximate patients had sufficient viral load for further genetic testing. Only 2 of these cases, both of whom underwent laryngoscopy, and their 4 proximates agreed to further testing. None of the 4 remaining proximate patients who underwent colonoscopy agreed to further testing. Mean genetic distance between the 2 case patients and 4 proximate patients ranged from 13.5% to 19.1%.

Conclusions.

Our investigation revealed that exposure to improperly reprocessed ENT endoscopes did not result in viral transmission in those patients who had viral genetic analysis performed. Any potential transmission of BBPs from colonoscopy remains unknown.

Is peracetic acid suitable for the cleaning step of reprocessing flexible endoscopes?

The bioburden (blood, protein, pathogens and biofilm) on flexible endoscopes after use is often high and its removal is essential to allow effective disinfection, especially in the case of peracetic acid-based disinfectants, which are easily inactivated by organic material. Cleaning processes using conventional cleaners remove a variable but often sufficient amount of the bioburden. Some formulations based on peracetic acid are recommended by manufacturers for the cleaning step. We performed a systematic literature search and reviewed the available evidence to clarify the suitability of peracetic acid-based formulations for cleaning flexible endoscopes. A total of 243 studies were evaluated. No studies have yet demonstrated that peracetic acid-based cleaners are as effective as conventional cleaners. Some peracetic acid-based formulations have demonstrated some biofilm-cleaning effects and no biofilm-fixation potential, while others have a limited cleaning effect and a clear biofilm-fixation potential. All published data demonstrated a limited blood cleaning effect and a substantial blood and nerve tissue fixation potential of peracetic acid. No evidence-based guidelines on reprocessing flexible endoscopes currently recommend using cleaners containing peracetic acid, but some guidelines clearly recommend not using them because of their fixation potential. Evidence from some outbreaks, especially those involving highly multidrug-resistant gram-negative pathogens, indicated that disinfection using peracetic acid may be insufficient if the preceding cleaning step is not performed adequately. Based on this review we conclude that peracetic acid-based formulations should not be used for cleaning flexible endoscopes.

Steps of reprocessing and equipments

With the increasing interest in endoscopy and the rising number of endoscopic examinations in hospitals, the importance of endoscopic reprocessing is also increasing. Cure facilities that are understaffed and ill-equipped are trying to cope with the problems of insufficient cleaning and high infection risks. To prevent endoscopy-associated infection, the endoscope cleaning, and disinfection guidelines prepared by the Korean Society of Gastrointestinal Endoscopy must be followed. In this review, the steps of endoscopic reprocessing and the equipments required in each step are discussed.

Better instructions for use to improve reusable medical equipment (RME) sterility

OBJECTIVE

The objective was to evaluate human-factors-based instructional aids on endoscope reprocessing.

BACKGROUND

The project stems from recent failures in reprocessing (cleaning) endoscopes, contributing to the spread of harmful bacterial and viral agents between patients. A previous study discovered three themes that represent a majority of problems: (1) lack of visibility (parts and tools were difficult to identify), (2) high memory demands, and (3) insufficient feedback.

METHOD

In an effort to improve completion rate and reduce error, the authors designed instructional aids utilizing human factors principles that would replace existing manufacturer-provided visual aids. Then, they conducted a usability test, which compared the endoscope reprocessing performance of novices using the standard manufacturer-provided visual aids and the new instructional aids.

RESULTS

Participants in the experimental group successfully completed 87.1% of the reprocessing procedure with the use of the instructional aids, compared to 44.7% in the control group using only existing support materials. Of 60 subtasks, 27 showed significant improvement in completion rates.

CONCLUSION

When given an instructional aid designed with human factors principles, participants were able to more successfully complete the reprocessing task. This resulted in an endoscope that was more likely to be safe for use on patients.

APPLICATION

The human factors design elements utilized to create the instructional aids could be transferred to a dynamic electronic-based system to improve patient safety.

Comparison of adenosine triphosphate, microbiological load, and residual protein as indicators for assessing the cleanliness of flexible gastrointestinal endoscopes

BACKGROUND

This study evaluated 3 potential indicators of gastrointestinal endoscope cleanliness: adenosine triphosphate (ATP), microbiological load, and protein.

METHODS

Before and after cleaning, ATP and microbiological load were determined from swabs of exterior surfaces and rinses of interior suction/accessory channels. Similarly, before and after cleaning, residual protein was determined from rinses of interior suction/accessory channels.

RESULTS

Before cleaning, ATP values were 10,417 relative light units (RLU) from the exterior endoscope surface and 30,281 RLU from the suction/accessory channel rinsates. After cleaning, these ATP values were decreased to 82 RLUs and 104 RLUs, a statistically significant difference. A similar trend was observed with microbiological load, but the change in residual protein from before cleaning to after cleaning was not significant. ATP values reliably reflected microbiological colony counts.

CONCLUSIONS

ATP measurement can provide a reliable, rapid and practical assessment of endoscope cleanliness for routine monitoring in the clinical setting.

Analysis of the air/water channels of gastrointestinal endoscopies as a risk factor for the transmission of microorganisms among patients

BACKGROUND

For the effective reprocessing of gastrointestinal endoscopes, contaminants must be removed from the entire surface. However, these devices have long and narrow channels that can make this process difficult.

METHODS

In this cross-sectional study, the staff assigned to reprocess gastroscopes and colonoscopes in 37 services located throughout Brazil completed a questionnaire regarding reprocessing practices geared toward the channels in these devices. In addition, samples from these air/water channels were collected for microbiological analysis.

RESULTS

Contamination was detected in 71.8% (28/39) of the samples obtained from the air/water channels of colonoscopes, and in 70% (42/60) of the samples from the air/water channels of gastroscopes. The median microbial load was 1,800 colony-forming units (CFU)/mL in the colonoscopes and 750 CFU/mL in the gastroscopes. The main microorganisms isolated from the air/water channels of gastroscopes were Pseudomonas aeruginosa (26.4%), Escherichia coli (18.9%), and Acinetobacter baumannii (9.4%), and those isolated from the colonoscopes included P aeruginosa (46.4%), A baumannii (14.3%), and Klebsiella pneumoniae (10.7%), among others. The possible causes of the contamination of these devices included the failure to fill these channels with cleaning solution, lack of friction during cleansing, and inadequate rinsing.

CONCLUSION

The contamination of the air/water channels did in fact represent a risk for the transmission of microorganisms during gastrointestinal endoscopy exams, possibly related to the inadequate reprocessing of these channels.

Prospective study of cross-infection from upper-GI endoscopy in a hepatitis C-prevalent population

BACKGROUND

A high prevalence of hepatitis C (HCV) in the Egyptian Nile Delta increases the demand for upper-GI endoscopy (UGIE) and the risk of cross-infection with this virus.

OBJECTIVE

To assess the potential for UGIE to transmit HCV when endoscopes are reprocessed according to current international standards.

DESIGN

A prospective cohort study to detect the incidence of HCV and hepatitis B cross-infections.

SETTING

The endoscopic unit of the National Liver Institute, a hospital for patients with chronic liver disease.

PATIENTS

A total of 859, including 149 of 249 patients (60%) at risk (HCV-antibody negative) retested 3 to 10 months after UGIE with endoscopes previously used on HCV carriers.

INTERVENTIONS

Nurses were trained to process endoscopes according to American Society for Gastrointestinal Endoscopy guidelines, and procedures were observed and recorded.

MAIN OUTCOME MEASUREMENTS

Seroconversions were determined by using enzyme immunoassays for anti-HCV; reverse transcriptase-polymerase chain reaction was used to detect HCV-ribonucleic acid (RNA).

RESULTS

Four patients, initially negative, tested positive for anti-HCV after UGIE. However, 2 of these had HCV-RNA in their baseline blood sample, and the other 2 did not have HCV-RNA in their follow-up sample.

LIMITATIONS

Very-high prevalence of anti-HCV in subjects reduced the proportion at risk of infection, and follow-up was difficult.

CONCLUSIONS

There were no cases of proven transmission of HCV when endoscopes were reprocessed by using currently accepted standards. This negative study is encouraging, because patients undergoing UGIE in the Nile Delta of Egypt where HCV-caused liver disease is so pervasive would be at maximum risk of HCV cross-infection from UGIE.

Audit of nasendoscope disinfection practice

INTRODUCTION

Several options exist with regard to flexible pharyngo-laryngoscope sterilisation. We audited the use of disposable sheaths in our department over a six-month period.

METHODS

A cost-analysis was performed and the advantages and disadvantages of this system were compared with several alternative options.

RESULTS

We found that the overall cost of disposable sheaths averaged ł4008 per month over a six-month period. We subsequently introduced chlorine dioxide (ClO2) wipes as a means of disinfection. Chlorine dioxide wipes have enabled a monthly saving of ł3145 over sheath usage. Additionally, they meet health regulation requirements and are a convenient, cost-effective alternative to sheaths.

DISCUSSION

The limiting factors, including time and financial issues, involved in nasendoscope disinfection are discussed.

CONCLUSIONS

We have found chlorine dioxide wipes to be a satisfactory alternative means of nasendoscope disinfection. Possible time constraints aside, there are no advantages of sheath use over our current method. Chlorine dioxide wipes are also preferable from a financial point of view.

Real-time monitoring in managing the decontamination of flexible gastrointestinal endoscopes

OBJECTIVES

To evaluate the efficacy of endoscope reprocessing using bacteriologic methods and adenosine triphosphate (ATP) bioluminescence and to evaluate the potential benefits of the latter in managing the process.

SETTING

An endoscopy unit in each of 2 acute district general hospitals in the United Kingdom.

METHODS

Following visual observation, 8 locations important in the decontamination of gastrointestinal (GI) endoscopes were monitored during reprocessing by bacteriologic sampling (paddle method) and ATP bioluminescence.

RESULTS

Endoscope reprocessing was conducted in accordance with British Society of Gastroenterology guidelines. Bacteriologic tests required 24 hours for results to be obtained; ATP tests were completed within 2 minutes. Of the 504 sites tested throughout the decontamination process, bacterial growth was recorded on 32 occasions, 3 from the end product. Throughout the decontamination process, ATP tests obtained 95 results above benchmark values and 1 from the end product.

CONCLUSIONS

The bacteriologic results after terminal disinfection indicated that the reprocessing was carried out effectively overall. ATP results prior to disinfection indicated that manual cleaning might not have always been performed adequately and that this could have impaired the disinfection process. ATP provided a rapid means of assessing the efficacy of cleaning steps prior to terminal disinfection.

Efficacy of 10 different cleaning processes in a washer–disinfector for flexible endoscopes

Successful cleaning of medical devices, such as flexible endocopes, has been recognized to be of major importance for effective processing. Washer-disinfectors (WD) are considered to be an important step in this direction. The cleaning process in WD, however, has only been partially assessed regarding its effectiveness, and therefore to study this in more detail, tests were carried out, according prEN ISO 15883, using transparent teflon tubes as test pieces (length 2 m). For each experiment three test pieces were contaminated with the 'German test soil' containing Enterococcus faecium in blood, two for the test and one as a control (no automatic cleaning). Automatic cleaning was performed with a Wassenburg WD 440. Ten cleaning agents were used. In addition the process was carried out with water alone. After automated cleaning, test pieces were assessed visually (four categories, range: very poor to excellent visible cleanliness) and microbiologically [log(10) reduction factor (RF)]. Each experiment was repeated three times. Using the WD water gave excellent visible cleanliness with a mean RF of 1.1+/-0.6. The same excellent visible cleanliness was obtained with seven cleaning processes: deconex 23 Neutrazym, Helimatic Cleaner enzymatic, Korsolex-Endo-Cleaner, Labomat E, neodisher mediclean, Thermosept ER, and Thermoton NR. Worse visible cleanliness was found with three cleaning processes: Olympus ETD Cleaner and neodisher FE led to adequate visible cleanliness, and the cleaning process with neodisher medizym led to poor visible cleanliness. Six cleaning processes reduced the test organism by RF>or=3, i.e. the reduction was significantly higher than after cleaning with water alone. No significant difference between use of water alone and the cleaning process was found with three cleaning processes: Olympus ETD Cleaner, neodisher mediclean, and Thermosept ER (range RF: 0.8-1.8; P > 0.05). The cleaning process with neodisher medizym yielded a significantly lower mean RF (P = 0.039) in comparison with water treatment alone. Both visible cleanliness and mean RF, varied indicating that the choice of cleaning process had a major impact on the overall result.

Cleaning efficacy of nine different cleaners in a washer-disinfector designed for flexible endoscopes

Studies on processing endoscopes usually involve the combined cleaning and disinfecting activity. We compared nine cleaning agents designed for automatic processing for cleaning efficacy alone using soft and hard water as controls in 12 different processes in a washer-disinfector. Experiments were performed according to the German Endoscopy Working Group recommendations using transparent Teflon tubes (internal diameter 2mm, length 2m) as test pieces. For each test three pieces contaminated with a blood/test soil containing Enterococcus faecium were used; two for the test and one as a control; each test was repeated three times. Tests were run according to the manufacturer's instructions. Test pieces were assessed visually and microbiologically [log(10) reduction factors (RF) vs. untreated controls]. Soft water alone gave poor visible cleanliness and an RF of 0.3 (SD 0.2), while hard water produced adequate visible cleanliness and an RF of 1.2 (SD 1.0). Five processes gave better visible cleanliness than soft water, but only three were better than hard water. Six processes were worse than soft water and five worse than hard water. Nine processes gave a better microbiological reduction factor than soft water, but the difference was only statistically significant in three. Only one process yielded a significantly higher RF than hard water; three were significantly worse. None of the cleaning processes reached the RF of 4 specified in the US regulations. This study confirms the variability of cleaning processes to dissolve blood residues and reduce the bioburden. We do not recommend abandoning cleaning agents, but suggest that further research is needed to clarify the relationships between washer-disinfectors, cleaning agents, and cleaning performance.

Contamination of single-use biopsy forceps: a prospective in vitro analysis

BACKGROUND

It has been suggested that single-use biopsy forceps prevent interpatient transmission of infection during endoscopy. Passage of sterile forceps through the accessory channel of the endoscope may lead to contamination, however, if the endoscope has been inadequately processed. The potential for contamination of single-use biopsy forceps at various stages of endoscope reprocessing was prospectively evaluated.

METHODS

A total of 50 disposable biopsy forceps were passed through the accessory channels of 10 colonoscopes at the following stages of reprocessing: (1) before use in patients to establish a baseline of high-level disinfection, (2) directly after colonoscopy to confirm contamination with use, (3) after manual cleaning and flushing of the accessory channel to support the claim that manual cleaning significantly decreases bioburden, (4) after manual cleaning and a 2-minute soak in 2% glutaraldehyde to assess for contamination after an inadequate cleaning time, and (5) after manual cleaning and a 20-minute soak in 2% glutaraldehyde. The forceps were then sealed in sterile plastic bags after adding 20 mL of thioglycollate broth medium. The suspension was passed through a 0.2-micron vacuum filter and the filters were cultured. All cultures were incubated more than 48 hours.

RESULTS

Biopsy forceps underwent a total of 50 aerobic and 50 anaerobic cultures. Colony-forming units too numerous to count of GI flora, including Escherichia coli, Klebsiella, Pseudomonas, and Clostridium species, grew on 19 of 20 culture plates from biopsy forceps passed through colonoscopes immediately after use. One plate in this group grew 3 colony-forming units of E coli. Persistence of GI flora was noted on 5 of 20 plates after manual cleaning of the colonoscopes. No GI flora were found on forceps after the colonoscopes after soaking in gluteraldehyde for 2 and 20 minutes. Environmental contaminants including diptheroids, Staphylococcus, and Streptococcus species grew on 16 culture plates.

CONCLUSIONS

(1) Single-use biopsy forceps are highly susceptible to contamination during passage through the accessory channels of improperly cleaned endoscopes. (2) Disinfection of the colonoscopes in this study prevented contamination of the forceps at baseline and after reprocessing. (3) Proper endoscope reprocessing may be the most important factor in preventing biopsy forceps-related interpatient infection.