Dr. Frank Bakker offers an insight in to best practice in endoscope reprocessing, in the wake of heightened concerns over the potential threat posed by COVID-19 – providing an overview of the latest evidence and guidance.
Endoscopy related infections pose a potential threat for healthcare systems worldwide. Infection outbreaks with highly resistant microorganisms have highlighted the problems of contaminated endoscopes.1 Outbreaks may increase morbidity and mortality, prolong hospital stays, and lead to secondary transmission to patients and staff.1 Although the exact number of infections is unclear, contaminated flexible endoscopes have been reported as the vector for transmission of infections for many years.2
To date, there have been no confirmed reports of SARS-CoV-2 (the virus that causes COVID-19) transmission through endoscopic procedures. However, many characteristics of the virus including its stability on various surfaces and modes of transmission, make gastrointestinal (GI) endoscopy a potentially high-risk procedure for COVID-19 transmission.3
There are a number of possible ways in which SARS-CoV-2 viral transmission could occur including person-to-person via direct contact with the virus, respiratory droplets, generation of infected aerosols during endoscopy, and through contact with contaminated endoscopic equipment, accessories and body fluids. Both upper and lower GI endoscopy procedures carry the risk of transmission of COVID-19.3
The additional risk of SARS-CoV-2 cross-infection is significant, as nonemergency endoscopies have only recently started taking place again. Data from the National Endoscopy Database indicate that total endoscopic activity fell to 5% of normal levels during the peak phase of the COVID-19 epidemic in the UK (down from approximately 35,000 reported procedures per week to 1,700 for the week ending 13 April 2020).4 As the number of procedures increases, the need to ensure optimum infection prevention and control strategies will rise exponentially. Cleaning and reprocessing of flexible endoscopes to the highest standards will form a key component of these strategies.
Flexible endoscopes are reusable, highly complex devices which require considerable care during the essential decontamination process. Most flexible gastrointestinal endoscopes cannot withstand the conditions used in a steam sterilisation process. So, unlike rigid endoscopes, they cannot be autoclaved, yet still present a risk of infection if contaminated during use.5
Flexible endoscopes, which make contact with mucous membranes but do not penetrate sterile areas of the body, are generally reprocessed by high level disinfection rather than sterilisation. The term ‘high level disinfection’ is given to the process which is used to eliminate or kill all vegetative bacteria, mycobacteria, fungi and viruses (including coronaviruses).
The BSG (British Society for Gastroenterology) recommends that a guiding principle for decontamination is that ‘any patient must be considered a potential infection risk, and each endoscope and device must be reprocessed with the same rigour following every endoscopic procedure’.5 This advice is particularly relevant today, when SARS-CoV-2 presents an ongoing risk.
Most flexible endoscopes are designed with multiple channels, which are difficult to clean and disinfect. The ability of microorganisms to form biofilms on the inner channel surfaces can therefore contribute to failure of the decontamination process.6 Natural bioburden levels detected on flexible GI endoscopes range from 105 CFU/ ml to 1010 CFU/ml after clinical use but effective cleaning reduces the number of microorganisms and organic debris by 4 logs, or 99.99%.6
It is now widely accepted that although COVID-19 is predominately spread by respiratory droplets, the virus is also present in infected stools and may be detectable for several weeks after clinical recovery.2 SARS-CoV-2 viral shedding in stools has been reported both in symptomatic and asymptomatic patients. In infected patients the SARS-CoV-2 virus has been detected in stool samples in up to 50% of cases.2 This is similar to other coronaviruses such as SARS-CoV-1 and MERS-CoV. In SARS-CoV-1 infection, persistent stool viral shedding was observed to occur beyond the second week of infection.2
Similarly, SARS-CoV-2 has been found in stool samples at day 17 in asymptomatic individuals with prior exposure to the virus.2 Whether stool shedding of viral particles can transmit infection is, at present, unclear.7 However, all endoscopic and decontamination procedures should be performed with stringent safety precautions and awareness that they may pose a risk of SARS-CoV-2 transmission.7
As SARS-CoV-2 is also known to be transmitted via fomites, there is a risk of viral transmission to patients via contaminated endoscopes, as has happened previously with hepatitis B and C and various multidrug resistant organisms.3
The shedding of SARS-CoV-2 viruses in faeces means COVID-19 could be transmitted by contaminated endoscopes, which could theoretically occur due to contact with mucous membranes and body fluids. As GI endoscopies involve close contact with colonic contents this can increase the risk of contamination and contribute to virus transmission.2
Even before the current pandemic, outbreaks of infections with highly resistant micro-organisms, highlighted the problems of contaminated endoscopes and lapses in the correct reprocessing of flexible endoscopes have been recorded in the pre-cleaning as well as in the automated reprocessing stages.2
Effective reprocessing of flexible endoscopes involves pre-cleaning, leak testing, cleaning and high level disinfection followed by rinsing and drying before storage.1 Cleaning must precede high level disinfection to remove organic debris (e.g. blood, faeces, respiratory secretions) from the external surface, lumens and channels of flexible endoscopes. Inadequate cleaning of flexible endoscopes has been frequently associated with microbial transmission during endoscopic procedures.6
The manual cleaning procedure for flexible endoscopes includes brushing of the external surface and removable parts (e.g. suction valves) and immersion in a detergent solution followed by irrigation of internal channels with a detergent. The endoscope and accessories should be inspected for damage and a leak test should be performed before disinfection.6
Automated Endoscope Reprocessors (AER) are strongly recommended for the reprocessing of flexible endoscopes to minimise contamination and contact with chemicals and soiled instruments. However, a defective AER can result in inadequate reprocessing. The presence of biofilms in defective AERs has been detected during these failings.6
According to the Joint Advisory Group on Endoscopy (JAG), infection prevention measures for reprocessing endoscopes should be put in place by Trusts, in line with national guidance. This should be supported by standard operating procedures (SOPs) and updated as further guidance is published.8 Decontamination best practice should be followed especially in red sites. This includes the reprocessing of endoscopic equipment immediately after use with strict adherence to manual cleaning processes. Red refers to areas or patient pathways with proven or suspected COVID-19.8
As a part of preparing and implementing robust Standard Operating Procedures, the choice of cleaners and disinfectants used in the reprocessing process is a key consideration. The decontamination process involves mechanical and detergent cleaning, followed by high-level disinfection, rinsing and drying.9
The cleaning stage is essential to the efficacy of the subsequent disinfection stage. Cleaning refers to the removal of soil and other organic contaminations from a device using the physical action of scrubbing and the chemical action of a detergent. Cleaning not only removes gross contamination, but, in addition, removes large numbers of microorganisms, which reduces the levels of organic bioburden on these surfaces. This process is designed to remove organisms rather than kill them9 and the choice of a suitable detergent is a key factor. It must always precede disinfection and helps to ensure the efficacy of the subsequent disinfection step,10,11 especially on surfaces like endoscopes with visible contamination
The BSG stipulates that thorough manual cleaning with a CE marked detergent must be undertaken before the endoscope is placed in the washer disinfector. The manual cleaning stage should include the brushing and flushing of all accessible endoscope channels.5 Cleaning is also carried out in the AER before high level disinfection.
The selected detergent must be compatible with the disinfectant used in the AER.5 If soil and bacterial biofilms are not removed from the endoscope, this will adversely impact on the efficacy of the disinfectant which then increases the risk of nosocomial infection.10 The use of highly effective formulations designed specifically for use in the manual cleaning (e.g. gigazyme) or automated cleaning (e.g. thermosept EndoCleaner) of endoscopes may be considered.
The ideal detergent cleansing agent should effectively permeate contaminants that contain proteins, lipids, carbohydrates and various chemical bases and separate the contaminants from the channels without damaging the endoscope.12 It should also be low-foaming to ensure maximum contact with the surface with the endoscope.12 The selected detergent must be compatible with the disinfectant used. This is because some detergents leave residues which can neutralise the active ingredient in certain disinfectants, thereby reducing the microbial killing properties of the disinfectant.
At the disinfectant stage, the ideal chemical high-level disinfectant should have the following qualities (according to the BSG, 2016): a broad antimicrobial spectrum; prolonged shelf life; be rapidacting, non-corrosive, and not harmful to the scope and its parts; non-toxic to humans and the environment; odourless and non-staining; cost effective; and capable of being monitored for concentration and effectiveness. Summarised into four key qualities, the ideal high-level disinfectant should have effective and proven antimicrobial efficacy (including against enveloped viruses such as coronaviruses), comply with all relevant regulations, norms and guidelines, demonstrate excellent material compatibility and ensure the safety of patients and staff.
Disinfectants based on peracetic acid (PAA) are widely used in the UK, as PAA has an extremely broad spectrum of antimicrobial activity. Depending on its concentration and pH value, it is effective against bacteria including Helicobacter pylori, fungi, mycobacteria, enveloped viruses including coronaviruses and Hepatitis B virus (HBV), non-enveloped viruses including parvovirus, and bacterial spores13
PAA is one of the few powerful antimicrobial agents available for use as a sporicidal agent, which is significant as spores are resistant to several stresses, such as heat, ultra-violet light, and most disinfectants14 The oxidising active PAA also helps remove biofilm from endoscopes.14
In addition to its broad antimicrobial spectrum, PAA has a short contact time for bacteria, including Mycobacterium tuberculosis, fungi, viruses and spores of around five minutes. This is in contrast to disinfectants based on ortho-phthalaldehyde (OPA) or glutaraldehyde (GDA) which have lengthy contact times of up to 10 hours for GDA and up to 32 hours for OPA. For example, CE marked thermosept PAA has a contact time of five minutes at 37˚C for the chemothermal reprocessing of flexible endoscopes in an AER.
HTM 01-06 (2016)15 warns that some chemicals may damage endoscopes. Therefore, any cleaner selected should be compatible with the range of endoscopes in use, as well as with the AER. All chemicals used in the AER process should be CE-marked, which indicates that the manufacturer has verified that these products meet EU safety, health and environmental standards. When the endoscope and cleaner are used together, they must be compatible and the importance of this should not be underestimated. The manufacturer of the cleaner/disinfectant must demonstrate that the products are designed and manufactured in such a way as to be used safely with the materials.
The COVID-19 pandemic has placed extraordinary demands on healthcare provision. As endoscopic diagnostic services resume, the need for stringent infection control strategies, including the use of optimum cleaners and disinfectants is essential to minimise viral transmission and reduce the attendant risks to both patients and staff.
About the author
Dr. Frank Bakker received his M.Sc. in chemical engineering from the University of Twente, the Netherlands and his Ph.D. in molecular biology from the University of Erlangen, Germany. 15 years ago, he started his career in medical device reprocessing and infection prevention as a process engineer for a leading manufacturer of washer disinfectors. Since 2010, he has been working for Schülke and Mayr, where he is the Head of the Application Department.
References 1 Kenters N. et al. Endosc Int Open. Infectious diseases linked to cross-contamination of flexible endoscopes 2015 Aug; 3(4): E259–E265. 2 Perisetti, A., Gajendran, M., Boregowda, U., Bansal, P. and Goyal, H. (2020), COVID-19 and gastrointestinal endoscopies: Current insights and emergent strategies. Digestive Endoscopy, 32: 715-722. 3 Rana S. S., Risk of COVID-19 Transmission During Gastrointestinal Endoscopy, March 2020 Journal of Digestive Endoscopy 11(01):27-30 4 Hayee B, et al. Safely restarting GI endoscopy in the era of COVID-19, BMJ Gut, 2020 5 BSG Guidance for Decontamination of Equipment For Gastrointestinal Endoscopy, The Report of a Working Party of the British Society of Gastroenterology Endoscopy Committee March 2014, Revised November 2016 6 Kovaleva, J., Peters, F., van der Mei, H. and Degener, J. (2013). Transmission of Infection by Flexible Gastrointestinal Endoscopy and Bronchoscopy. Clinical Microbiology Reviews, 26(2), pp.231-254. 7 Iacucci M. et al, Endoscopy in inflammatory bowel diseases during the COVID-19 pandemic and postpandemic period; Lancet Gastroenterol Hepatol 2020; 5: 598–606 8 JAG accreditation Supplementary environment guidance following the COVID-19 pandemic Published 21 May 2020 9 Calderwood AH, Day LW, Muthusamy VR, et al, ASGE guideline for infection control during GI endoscopy, Volume 87, No. 5 : 2018 Gastrointestinal Endoscopy 10 Vickery K, The effect of multiple cycles of contamination, detergent washing, and disinfection on the development of biofilm in endoscope tubing, American Journal of Infection Control, 2009, Vol 37, issue 6, Pages 470-475 11 Quinn M. M.,Henneberger P.K., et al, Cleaning and disinfecting environmental surfaces in health care: Toward an integrated framework for infection and occupational illness prevention, American Journal of Infection Control 43 (2015) 424-34 12 Lee YK, Park JB, Steps of Reprocessing and Equipments, Clin Endosc 2013;46:274-279 13 Kampf G., Fliss P.M., Martiny H., (2014). Is peracetic acid suitable for the cleaning step of reprocessing flexible endoscopes? World J Gastrointest Endosc 16; 6(9): 390-406 14 Matsumura, Y., et al (2006). Antimicrobial activity of peracetic acid preparation in the in presence of various compounds, Technology Reports of Kansai University 15 Department of Health, Health Technical Memorandum 01-06: Decontamination of flexible endoscopes Part C: Operational management, March 2016
