ENDOSCOPIC DISINFECTION GUIDELINES

MALAYSIAN SOCIETY OF
GASTROENTEROLOGY & HEPATOLOGY

2006

Panel Members:
Dr. Ryan Ponnudurai
Assoc. Prof. Dr. Sanjiv Mahadeva
Dr. Abraham George
Mary Bong

Flexible endoscopes are complex reusable instruments that require unique consideration with respect to decontamination. In addition to the external surface of endoscopes, their internal channels are exposed to body fluids and other contaminants.

Transmission of infection at endoscopy
A guiding principle for disinfection is that of universal precautions: any patient must be considered a potential infection risk, and each endoscope must be decontaminated with the same rigour following every endoscopic procedure.There have been concerns regarding the transmission of Hepatitis C virus (HCV) following an instance report in 1997 (1). Adherence to the following reprocessing guidelines should effectively eliminate the risk of HCV transmission from endoscopy.

During the last 20 years glutaraldehyde based products have been the most commonly used disinfectants in endoscopy units worldwide. Most reports of transmission of bacteria such as pathogenic E. Coli, Salmonella, Pseudomonas, Enterobacter and Serratia spp. predate the introduction of glutaraldehyde for disinfection. (2)

Three types of micro organisms have merited particular attention in recent years. (3)

1. Mycobacteria: The emergence of multi drug resistant strains of Mycobacterium tuberculosis and the high incidence of infections with M.avium intracellulare among HIV infected patients has led to a greater awareness for transmission during bronchoscopy. Mycobacterium in general are extremely resistant to glutaraldehyde.
2. Bacterial spores (Bacillus and Clostridium): Spores from these organisms have been isolated from endoscopes but there has been no reported cases of transmission of these infections by endoscopy.
3. Pathological Prions including Creutzfeld Jacob Disease: These infection organisms are extremely resistant to standard decontamination procedures. (4)
   

General Considerations:
Sterilisation is defined as the complete destruction of all micro-organisms including bacterial spores. Sterilisation is required for devices that are normally used in sterile areas of the body (e.g. laparoscopes, microsurgical instruments). Flexible endoscopes (which make contact with mucous membranes but do not ordinarily penetrate normally sterile areas of the body) are generally reprocessed by high level disinfection rather than sterilisation in order to kill bacteria, viruses, mycobacteria and some spores. Most flexible gastrointestinal endoscopes would not withstand the conditions normally used in a steam sterilisation process.

Endoscopes are routinely exposed to mucus and other gastrointestinal secretions, blood, saliva, faeces, bile, and sometimes pus. The process of decontamination comprises two basic components:

a)	manual cleaning, which includes brushing with single-use wire brushes, and exposure of all external and accessible internal components to a low-foaming enzymatic detergent known to be compatible with the endoscope;
b)	automatic disinfection, rinsing and drying of all exposed surfaces of the endoscope.

Failure to follow these recommendations may not only lead to transmission of infection, but also to misdiagnosis (e.g. if pathological material from one patient is included in specimens from the next patient) and to instrument malfunction and shortened lifespan.

Decontamination should begin as soon as the endoscope has been removed from the patient
The initial steps in the reprocessing protocol begin in the procedure room immediately after removal of the insertion tube from the patient and before removing the endoscope from the power source.

Have the following available :

• Personal protective equipment (gloves, eye protection, face protection and impervious gown).
• Container with enzymatic detergent solution.
• Sponge or soft, lint-free cloth.
• Air and water channel cleaning adapters per manufacturer's instructions.
• Protective video caps.

Immediately after removing the endoscope from the patient, wipe the insertion tube with a wet cloth or sponge soaked in the freshly prepared enzymatic detergent solution.

• Dispose of the cloth or sponge between cases.

Place the distal end of the endoscope into the enzymatic detergent solution. Suction the solution through the biopsy/suction channel until the solution is visibly clean. Alternate suctioning detergent solution and air several times. Finish by suctioning air.

• Alternate suctioning of fluid and air is more effective than suctioning fluid alone in the removal of debris from internal lumens.
• Immediate flushing of the biopsy/suction and air/water channels precludes drying of organic and inorganic debris on lumen surfaces and may remove large numbers or microorganisms.
• Blow out air and flush water channels in accordance with the endoscope manufacturer's instructions.
• Detach the endoscope from the light source and suction pump.
• Attach protective video cap.
• Transport the endoscope to the reprocessing area in a leak proof enclosed container.
• Containers, sink, and basins should be large enough that the endoscope will not be damaged by being coiled too tightly.
• A container will prevent contamination during transport.
• Reprocessing should occur in a room separate from the procedure room.
  

Cleaning the Endoscope in the Reprocessing Area:
Have the following available:

• Personal protective equipment (gloves, eye protection, impervious gown).
• Leakage tester equipment.
• Channel cleaning adapters (per manufacturer's instructions).
• Large basin of enzymatic detergent solution prepared according to the manufacturer's instructions.
• Channel cleaning brushes and lint-free cleaning swabs.
• Sponge and/or lint-free cloth.

LEAK TESTING:
Leak test the endoscope following manufacturer's instructions.

• Attach the leak tester and pressurize the scope before submerging it in water.
• Remove the detachable parts of the endoscope.
• With the pressurized endoscope completely submerged, flex the distal portion of the scope in all directions. Observe the insertion tube, distal bending section, and the universal cord for bubbles coming from the interior of the scope.
• The leak test will detect damage to the interior or exterior of the endoscope. The leak test is done before immersion of the endoscope in reprocessing solutions to minimize damage to parts of the endoscope not designed for fluid exposure.

Follow the manufacturer's instructions if a leak is detected or the endoscope appears damaged.

CLEANING:
Mechanical cleaning is the first and most important step in removing the microbial burden from an endoscope. Retained debris may inactivate or interfere with the capability of the active ingredient of the high level disinfectant to effectively kill and/or inactivate microorganisms. Cleaning gastrointestinal endoscopes is necessary before automated or manual disinfection.

• Fill a sink or basin with freshly made solution of water and a low-sudsing enzymatic detergent compatible with the endoscope.
• Dilute according to the detergent manufacturer's instructions.
• Use fresh detergent solution for each endoscope to prevent cross contamination.
• Low-sudsing detergents are recommended so that the device can be clearly visualized during the cleaning process to preclude personnel injury and to allow for complete cleaning of lumen surfaces. Excessive sudsing can inhibit good fluid contact with the device surfaces.
• Immerse the endoscope.
• Wash all debris from the exterior of the endoscope by brushing and wiping the instrument while submerged in the detergent solution.
• The instrument should be left under water during the cleaning process to prevent splashing of contaminated fluid.
• Detach the suction and air/water valves, the biopsy channel cover, the distal end hood, if present, and all other removable parts.
• The endoscope must be completely disassembled so that all surfaces may be reached for thorough cleaning.
• Brush all accessible endoscope channels including the body, insertion tube, and the umbilicus of the endoscope. Use a brush size compatible with each channel.
• Dilute according to the detergent manufacturer's instructions.
• After each passage, rinse the brush, removing any visible debris in the detergent solution before retracting and reinserting it.
• Continue brushing until there is no debris visible on the brush.
• Discard single-use channel cleaning brushes. Clean and high-level disinfect reusable brushes between cases. Reusable brushes should be inspected between uses and replaced when worn, frayed, bent, or otherwise damaged. Worn bristles are ineffective in cleaning, and damaged brushes may damage endoscope channels.
• Attach all cleaning adapters for suction, biopsy, air and water channels.
• Attach cleaning adapters for special endoscope channels (e.g. elevator channel, forward water jet, double-channel scopes).
• Because the elevator channels have small lumens, force greater than can be generated by an automated reprocessor is needed to force fluid through them. This channel requires manual reprocessing (all steps) using a 2- to 5-milliliter syringe. Although the elevator channels of these scopes have channel adapters that my be made to fit reprocessors, this channel must be manually reprocessed.
• Flush all channels with the detergent solution to remove debris.
• Thoroughly rinse the endoscope and all removable parts with clean water to remove residual debris and detergent.
• Purge water from all channels using forced air. Dry the exterior of the endoscope with a soft, lint-cloth to prevent dilution of the liquid-chemical germicide used in subsequent steps.
  

USING HIGH LEVEL DISINFECTION (HLD):

• Prepare the germicide according to the manufacturer's labeling instructions.
• Test the germicide for the Minimum Effective Concentration (MEC) on each day of use and more frequently as dictated by the number of endoscopes being reprocessed.
• Use the test strip specific for the brand of germicide. Keep a log of the test results.
• The MEC may not be used to extend the use-life claim of the germicide.
  

CHOICE OF DISINFECTANTS
The ideal disinfectant would be:

• Effective against a wide range of organisms including blood-borne viruses and prion proteins.
• Compatible with endoscopes, accessories and endoscope reprocessors.
• Non-irritant and safe for users.
• Environmentally friendly for disposal.
  

Other factors that will influence the choice of disinfectant include the process of dilution, stability of the solution, number of reuses possible, and the cost of using the particular disinfectant (e.g. costs of the appropriate automatic endoscope reprocessors, storage space, and conditions required for use, including staff protection measures).

Although less irritant than glutaraldehyde, orthophthalaldehyde, peracetic acid and chlorine dioxide are all potential skin and respiratory sensitisers. Therefore the same precautions should be taken when using these disinfectants, including fume extraction/containment and personal protective equipment.

Disinfectants commonly used:

a)	Aldehyde-based disinfectants
	A widely-used glutaraldehyde-based disinfectant (Cidex ®) is still widely used in Malaysia but has recently been withdrawn from the United Kingdom market by its manufacturer. This is not only because there have been advances in the development of disinfectants with superior bactericidal activity, but also because glutaraldehyde is chemically related to formaldehyde, and has similar toxic effects on skin and mucous membranes.(4) Resulting adverse effects include severe dermatitis, conjunctivitis, sinusitis and asthma. Glutaraldehyde has also been implicated as a cause of chemical colitis.(5) A further problem with glutaraldehyde-based disinfectants is their potential to cross-link residual protein material. The resulting amalgam is very difficult to remove from working channels of endoscopes that have been repeatedly flushed with aldehydes. This again underscores the importance of manual pre-cleaning and brushing of all accessible internal channels and valve chambers before disinfection. Glutaraldehyde and its derivatives kill most bacteria and viruses (including human immunodeficiency virus and hepatitis B) in less than five minutes. Mycobacteria are more resistant to 2% glutaraldehyde, and thus, the recommendation is that endoscopes are immersed for 20 minutes in 2% glutaraldehyde at room temperature.(6) Ortho-phthalaldehyde (0.55% solution marketed as Cidex OPA ®) is more stable and has a lower vapour pressure than glutaraldehyde. It is therefore practically odourless and does not emit noxious fumes. OPA is a potential skin and respiratory sensitiser and thus can aggravate pre-existing asthma, bronchitis or dermatitis. It is non-flammable and is stable at a wide pH range. It has better myobactericidal activity than 2% glutaraldehyde.(7) In use testing of OPA on endoscopes has shown cidal activity achieving a reduction of greater than five logs. and stability over a two-week period. The manufacturers of Cidex OPA ® recommend the daily use of OPA test strips to monitor the activity of reused batches of disinfectant solution. Each batch should be replaced after two weeks of use. OPA does not require pre-activation and can be discarded down hospital drains. It does not appear to damage instrument components, but like other aldehydes it can stain and cross-link protein material.
b)	Peracetic Acid
	This is marketed as NuCidex ® (0.35 % peracetic acid), Perasafe ® (0.26% peracetic acid), Perascope ® and Gigasept PA. Peracetic acid is also available as part of a dedicated disinfector called the Steris ® system (which uses 0.2% peracetic acid at 53ºC) Peracetic acid is a powerful oxidising agent that rapidly kills a wide range of micro-organisms. It has a broad spectrum of activity against viruses, vegetative bacteria, mycobacteria, fungi and spores. Its mycobactericidal activity is superior to that of glutaraldehyde, being effective against mycobacteria (including Mycobacterium avium) within 10 minutes.(8) Peracetic acid is more effective than glutaraldehyde at removing organic matter such as biofilms. Its rate of activity varies according to its use concentration and temperature. Bactericidal activity diminishes after 24 hours and therefore each batch should be changed each day. Peracetic acid can cause discolouration and peeling of electroplated components and rubber. The Steris ® system has been shown to be effective at eliminating vegetative organisms, fungi and spores and was effective in experimental models of antimicrobial efficacy.(9) The main drawbacks with the Steris ® system are that exposure to detergent is not included in its wash cycle, the instruments must be allowed to cool before use, and the instrument tray shape is unsuitable for the disinfection of Olympus ® endoscopic ultrasound scopes. Peracetic acid is a colourless liquid with a strong vinegary odour which is irritant, but it decomposes to carbon dioxide, oxygen and water and therefore does not pose an environmental hazard. The WATCH committee of the Health and Safety Committee have concluded that peracetic acid can cause skin reactions, and that there is a potential for provoking upper respiratory irritation. Peracetic acid should therefore be used with an exhaust ventilated system.

MANUAL DISINFECTION:

• Completely immerse the endoscope and all removable parts in a basin of HLD. The basin must be of a size to accommodate the endoscope without undue coiling and must have a tight-fitting lid to contain the vapors.
• Inject disinfectant into all channels of the endoscope until it can be seen exiting the opposite end of each channel. Take care that all channels are filled with HLD and that no air pockets remain within the channels. Complete microbial destruction cannot occur unless all surfaces are in complete contact with the HLD.
• Soak the endoscope in the HLD for the time/temperature required to achieve high level disinfection. Use a timer to verify soaking time.
• Flush all channels completely with air before removing the endoscope from the HLD.
• Purging the HLD from the channels preserves the concentration and volume of HLD and prevents exposure from dripping and spilling.

RINSING AFTER MANUAL DISINFECTION:

• Thoroughly rinse all surfaces and channels of the endoscope and its removable parts with large amounts of clean water.
• Rinsing prevents exposure and potential injury of skin and mucous membranes from chemical residue.
  

DRYING:

• Purge all channels with air. This is to prevent certain bacteria and fungi multiplying in a moist environment.
• Avoid the use of excessively high air pressure. High-pressure air can damage the internal channels of flexible GI endoscopes.
• Flush all channels, including accessory channels, with alcohol until the alcohol can be seen exiting the opposite end of each channel.
• 70 to 80% isopropyl alcohol is used as a solvent to assist in drying the interior channel surfaces. Alcohol mixes with the remaining water on the channel surfaces and acts to encourage evaporation of the residual water as air flows through the channel.
• Use fresh alcohol that has been properly stored in a closed container between uses. Alcohol, when exposed to air, rapidly evaporates, and if below the recommended percentage level, cannot be relied upon to assist in the drying process.
• Purge all channels with air. Air assists alcohol in evaporating any retained moisture.
• Remove all channel adapters.
• Dry the exterior of the endoscope with a soft, clean lint-free towel.
• Thoroughly rinse and dry all removable parts. Do not attach removable parts (valves, etc.) to the endoscope during storage.
  

STORAGE:

• Hang the endoscope vertically with the distal tip hanging freely in a well-ventilated, dust-free cabinet.
• Correct storage of the GI endoscope will prevent damage to the exterior of the device by protecting the device from physical impact.
• A storage cabinet with good ventilation will encourage continued air drying of the surfaces and prevent undue moisture buildup in the cabinet interior, thereby discouraging any microbial contamination of the cabinet surfaces.
  
  

AUTOMATED ENDOSCOPIC REPROCESSORS (AER's):

• Before using the automated reprocessor it must be stressed that manual cleaning is the single most important step in cleaning and disinfection. However the automated reprocessor is useful as it can standardize the disinfection process and reduce personel exposure to the chemical used for disinfection.
• When using the automated reprocessor the staff must ensure that all manufacturer's instructions are adhered to.
• A copy of work instruction on how to use the automated reprocessor must be available for reference in the GI unit. All staff involved in using the reprocessor must have easy access to the work instruction.
• It is essential that the machine is properly cleaned and disinfected at the start of each working day employing, where possible, the AER's self disinfection cycle. It is recommended that an agent other than that used for endoscope disinfection is used to disinfect the machine. Care should be taken to ensure that all disinfectants used are compatible with the AER, and are employed at the correct temperature and concentration.
• It is recommended that the final rinse water is tested for its microbiological quality on a weekly basis.
• The user should make daily checks of the filters and pipe work supplying rinse water. Water filters should be changed in accordance with the manufacturer's instructions, or more often if the water quality is poor (as suggested by frequent clogging of filters). Hard water can cause a deposit of limescale on internal pipe work.
• Newer machines have automatic leak-testing facilities incorporated within them, but these devices are not foolproof because they do not angle the endoscope tip during leak testing, and may therefore fail to recognise positional leaks.
• Older duodenoscopes do not have endoscope tips that can be detached to allow access to the elevator wire channel for cleaning. Some AERs have the capacity to deliver high-level disinfection to this channel. Users of duodenoscopes without detachable tips should pay special attention to the capability of their AERs in this respect. Manual cleaning and disinfection of the elevator wire channel may be necessary.
• Drying and storage are the same as described in manual disinfection.
  

SUMMARY:

1. Decontamination of endoscopes should be undertaken at the beginning and the end of each list, and between patients, by trained staff in dedicated rooms. Thorough manual cleaning with an enzymatic detergent, including the brushing of all accessible endoscope channels, must be undertaken before automatic endoscope disinfection.
   
   
2. All disinfectants should be used at the correct temperature in accordance with the manufacturers' instructions. Some manufacturers provide test strips and/or kits, the use of which they recommend in ensuring optimal activity of their product.
   
   
3. It is important to ensure that the endoscope manufacturer has approved the chosen disinfectant for use in decontaminating their product, and that the disinfectant is also compatible with the automatic endoscope reprocessor in which it is being used.
   
   
4. Two percent glutaraldehyde has historically been the most commonly used disinfectant in endoscopy units within the UK. Unfortunately this agent is irritant and sensitising, and adverse effects among endoscopy staff are common. The manufacturers of a widely-used glutaraldehyde-based product have now withdrawn this disinfectant largely due to health and safety concerns.
   
   
5. The use of isopropyl alcohol for flushing endoscope channels is recommended as part of the drying process at the end of the working day prior to storage.
   
   
6. Automated endoscope reprocessing machines should be used for all endoscope decontamination following manual precleaning. These machines are recommended both because they reliably expose all external and internal components of the endoscope to thorough disinfection and rinsing, and because they help prevent atmospheric pollution by the disinfectant. Automatic reprocessors must be reliable, effective and easy to use. Manual disinfection is no longer acceptable.
   
   
7. Water used in automatic endoscope reprocessors should be free of particulate contamination and of micro-organisms. This can be achieved either by using bacteria-retaining filters or by other methods, for example the addition of biocides. In-line water softeners may be needed if the local supply delivers hard water. The final rinse water should be sampled from the automatic reprocessor and tested for its microbiological quality at least weekly.
   
   
8. A record should be kept of the serial number of each endoscope used in each patient. This log should include any loan endoscopes. This is important for any future contact tracing when possible endoscopic transmission of disease is being investigated.
   
   
9. Endoscopy should be avoided whenever possible in patients with suspected or confirmed vCJD. When deemed essential either a dedicated endoscope should be used, or one nearing the end of its useful life can be employed and subsequently quarantined and reserved for similar patients in future. When percutaneous feeding gastrostomy or jejunostomy is required in such patients a dedicated endoscope should be used or the feeding tube deployed by radiological or surgical means.
   
   
10. The agent of variant Creutzfeldt-Jakob disease (vCJD) is resistant to all forms of conventional sterilisation. The risk of transmission of this agent is probably extremely low provided that scrupulous attention to detail is routinely employed in the decontamination process after every patient. In particular all accessible endoscope channels should be brushed through with a single use purpose-made brush tipped wire assembly that has an appropriate length and diameter for each channel.
    
    
11. 'Single use' or autoclavable accessories are preferred. Single use biopsy forceps, guidewires and cytology brushes should always be used in order to minimise any possible risk of transmitting prion disease. Rubber valves covering the working channel must be changed after all procedures involving the passage of biopsy forceps, guidewires and/or other accessories through the endoscope.
    
    
12. Health surveillance of staff is mandatory and should include a pre-employment enquiry regarding asthma, skin and mucosal sensitivity problems and lung function by spirometry. Occupational health records should be retained for 40 years.
    
    
13. Those involved in endoscopic practice should be immunised in accordance with local occupational health and infection control policies. All staff should wear single use gloves that are changed after each procedure. Staff involved in endoscope decontamination should also wear appropriate protective clothing.
    

References

Bronowicki JP, Vernard V, Botte C et al. Patient-to-patient transmission of hepatitis C virus during colonoscopy. New Engl J Med 1997;337:237-40. Technology Status Evaluation Report; Transmision of infection by gastrointestinal endoscopy. Gastrointest Endosc 2001;54:824-8. BSG Guidelines for decontamination of Equipment for Gastrointestinal Endoscopy. BSG workingpart report 2003(Updated 2005). The report of a working party of the British Society of Gastroenterology Endoscopy Committee Axon ATR, Beilenhoff U, Bramble MG et al. E.S.G.E Guidelines: Variant Creutzfeldt-Jakob Disease (vCJD) and gastrointestinal endoscopy. Endoscopy 2001; 33: 1070-80. Axon ATR, Beilenhoff U, Bramble MG et al. ESGE Guidelines on Cleaning and Disinfection in GI endoscopy. Endoscopy 2000;32(1):77-83. West AB, Kuan SF, Bennick M et al. Glutaraldehyde colitis following endoscopy: clinical and pathological features and investigation of an outbreak. Gastrointest Endosc 1995;108:1250-5. Cronmiller JR, Nelson DK, Salman G et al. Antimicrobial efficacy of endoscopic disinfection procedures: a controlled, multifactorial investigation. Gastrointest Endosc 1999;50:152-8. Walsh SE, Maillard JY, Russell AD. Orthophthalaldehyde: a possible alternative to glutaraldehyde for high level disinfection. J Appl Microbiol 1999;86:1039-46. Lynam PA, Babb JR, Fraise AP. Comparison of the mycobactericidal activity of 2% alkaline glutaraldehyde and NuCidex ®" (0.35% peracetic acid). J Hosp Infect 1995;30:237-40. Bradley CR, Babb JR, Ayliffe GA. Evaluation of the Steris System 1 Peracetic Acid Endoscope Reprocessor. J Hosp Infect 1995;29(2):143-51.

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