Endoscope reprocessing is a multi-step process demanding meticulous attention to detail. While it occurs away from the procedure room and the hustle and bustle of room turnovers, effective cleaning and disinfection of endoscopes is an integral part of a GI procedure. Avoiding transmission of infectious agents demands strict adherence to published reprocessing guidelines, particularly as endoscopic units become busier and the number of procedures performed nationwide increases.

Reprocessing done right
Flexible endoscopes are complex instruments with internal channels for air, water and accessories (see "Why Endoscopes Are Difficult to Reprocess" on page 34). When endoscopes are used for diagnostic or therapeutic procedures, body fluids and contaminants may remain on the instrument. Debris and microorganisms are removed from the endoscope during reprocessing, which involves detailed cleaning and high-level disinfection. In contrast to rigid endoscopes and some reusable accessories, flexible endoscopes are heat-labile and can't be steam sterilized.

Here are four steps recommended for effective reprocessing of gastrointestinal endoscopes.

• Mechanical cleaning. This initial step in endoscopic disinfection is the most critical.1 Mechanical cleaning removes a significant amount of organisms, feces and foreign material from the endoscope. Do this immediately after withdrawing the endoscope from the patient, with water, brushing and enzymatic detergents. Washing the endoscope's exterior and washing and brushing the interior channels and valves prevents the build-up of organic debris and decreases the bioburden, or degree of microbial contamination.

Without adequate manual cleaning, retained biofilm on the surface or in the channel of the endoscope can prevent further adequate disinfection regardless of the method employed.1 All subsequent steps in reprocessing an endoscope require meticulous initial cleaning of the device's internal and external surfaces.

• Disinfection. High-level disinfection is the current standard for reprocessing endoscopes, achieved by either automated reprocessors or by manual reprocessing.2 High-level disinfection requires complete immersion of the endoscope in disinfecting solution under specified conditions. The use of endoscopes that can't be fully immersed is unacceptable.

High-level disinfection destroys vegetative bacteria, viruses, fungi and mycobacteria, but not necessarily all bacterial spores. It's usually achieved through the use of meticulous manual pre-cleaning followed by exposure to a liquid chemical germicide (LCG).3

The FDA has approved LCGs for use in high-level disinfection.3 Such liquid chemical germicides may be used in both manual and automated reprocessing techniques. Glutaraldehyde (>2.4% concentration) remains the most commonly used LCG. Other commonly used LCGs include hydrogen peroxide 7.5%, peracetic acid 0.2%, ortho-phthalaldehyde 0.55% and peracetic acid 0.08% with hydrogen peroxide 1.0%.3,4

Many standards recommend that you may achieve high-level disinfection by immersion in 2.4% glutaraldehyde for at least 20 minutes at 20 ?C after the mechanical cleaning of an endoscope.5 This recommendation is in conflict with glutaraldehyde's labeling. In 1993, the FDA assumed jurisdiction over the regulation of clinical germicides and at that time required manufacturers of 2.4% glutaraldehyde (as part of the 510(k)-clearance process for medical devices) to label their product with a recommendation of 45 minutes of exposure to glutaraldehyde at 25 ?C.

The FDA's recommendation was based on the length of time and temperature needed for glutaraldehyde to kill 100 percent of Mycobacterium tuberculosis without manual pre-cleaning.6 Recognizing the crucial role of mechanical cleaning, subsequent guidelines have suggested that 20 minutes of glutaraldehyde immersion at room temperature is sufficient to achieve high-level disinfection after completing recommended pre-cleaning.

Current multi-society guidelines reflect this thinking.7 Glutaraldehyde is currently used in 67 percent of reporting centers at 2.4% concentration; 3.4% glutaraldehyde is used in another 13 percent. Additionally, 84 percent of centers use a 20-minute soak time, and only 24 percent of centers heat their glutaraldehyde solution.8

Potency testing of glutaraldehyde and other liquid chemical germicides used for endoscope disinfection must be done uniformly and regularly. As LCGs are reused, dilution occurs that can decrease the LCG's microbiocidal activity. Standards for infection control mandate regular monitoring of LCG concentration, so use product-specific test strips to make sure solutions remain above their minimum effective concentration. Current guidelines suggest that potency testing be done at least daily or more frequently as dictated by a high number of endoscopes being reprocessed or as directed by the germicide manufacturer.

Many endoscopy units now use automated endoscope reprocessors as part of their disinfection procedure. The use of an AER does not eliminate the need for manual cleaning.8,9

Despite the popularity of automated reprocessors, studies haven't shown a clear advantage for automated reprocessing over manual high-level disinfection.10 Automated reprocessors offer potential advantages to reprocessing personnel, such as decreased exposure to liquid chemical germicides, standardization of the disinfection process and a reduction in manual labor.

Disadvantages include higher cost, difficulties in accessing narrow channels (elevators in duodenoscopes, for example) and possible increased reprocessing time.11

• Rinsing. Rinsing the endoscope thoroughly after reprocessing with a LCG is critical in preventing residual germicide from contacting the GI mucosa of subsequent patients. Rinse the channels and the endoscope's external surface with copious amounts of water.7 Recommendations for rinsing suggest that it be done with sterile water or water filtered through 0.2 micron pores to decrease the risk of reintroducing microorganisms into the endoscope after high-level disinfection has been completed. Tap water may contain Pseudomonas, mycobacteria or other microorganisms.12
• Drying and storage. Drying is the final step in the reprocessing process, using 70% to 90% ethyl or isopropyl alcohol and forced-air drying.7 This step eliminates residual water that may be trapped in the channels of the endoscope, where such standing water may provide a suitable environment for the multiplication of microorganisms.

Not all guidelines stress the need for thorough drying after reprocessing, but many consider this step as important to the prevention of nosocomial infection as cleaning and high-level disinfection.13 Store endoscopes without coiling in a well-ventilated closet to prevent possible pooling of residual water.7,18 Some guidelines suggest the need to reprocess endoscopes before the day's first case, but several studies examining this suggestion have concluded that when reprocessed according to established guidelines and stored properly, flexible endoscopes remain free from pathogens overnight and for at least 7 days.13-16

Take every precaution
Reprocessing errors typically arise from human error or from the failure of the automated endoscope reprocessor or the high-level disinfectant.17 I can't overemphasize the importance of strictly adhering to multi-society reprocessing guidelines. Working with an adequately trained and dedicated reprocessing staff is critical to the success of any endoscope-reprocessing program.

Only well-trained personnel should perform manual cleaning and disinfection. A quality assurance program to ensure consistent procedures and adequate outcomes should be established in all endoscopic units. Be aware of the specifics of reprocessing in your GI unit, monitor guidelines regularly for updated recommendations and correct deficiencies when they occur.

References:
1. Chu NS, Favero M. The microbial flora of the gastrointestinal tract and the cleaning of flexible endoscopes. Gastrointest Endosc Clin North Am. 2000;20:233-44.
2. Nelson DB. Infection control during gastrointestinal endoscopy. J Lab Clin Med. 2003;141:159-67.
3. Rutala WA, Weber DJ. Disinfection of endoscopes: Review of new chemical sterilants used for high-level disinfection. Infect Control Hosp Epidemiol. 1999;20:69-76.
4. SGNA standards: Guideline for the use of high-level disinfectants and sterilants for reprocessing of flexible gastrointestinal endoscopes. Gastroenterology Nursing. 2000;23:180-7.
5. Rutala WA, Weber DJ. FDA labeling requirements for disinfection of endoscopes: A counterpoint. Infect Control Hosp Epidemiol. 1995;16:231-5.
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7. American Society for Gastrointestinal Endoscopy. Multi-society guidelines for reprocessing flexible gastrointestinal endoscopes. Gastrointest Endosc. 2003;58;1-8.
8. American Society for Gastrointestinal Endoscopy. Technology status evaluation report: Automatic endoscope reprocessors. Gastrointest Endosc. 1999:50:925-7.
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12. Muscarella LF. Application of environmental sampling to flexible endoscope reprocessing: The importance of monitoring the rinse water. Infect Control Hosp Epidemiol. 2002;23:285-9.
13. Muscarella LF. Inconsistencies in endoscope-reprocessing and infection control guidelines: the importance of endoscope drying. Am J Gastroenterol. 2006;101:2147-54.
14. Osborne S, Reynolds S, George N et al. Challenging endoscopy reprocessing guidelines: a prospective study investigating the safe shelf life of flexible endoscopes in a tertiary gastroenterology unit. Endoscopy. 2007;39:825-30.
15. Vergis AS, Thomson D, Pieroni P et al. Reprocessing flexible gastrointestinal endoscopes after a period of disuse: is it necessary? Endoscopy. 2007;39:737-9.
16. Pineau L, Villard E, Duc DL, et al. Endoscope drying/storage cabinet interest and efficacy. J Hosp Infect. 2008;68:56-65.
17. Rutala WA, Weber DJ. How to assess risk of disease transmission to patients when there is failure to follow recommended disinfection and sterilization guidelines. Infect Control Hosp Epidemiol. 2007;28:146-55.
18. American Society for Testing and Materials: Standard practice for cleaning and disinfection of flexible fiberoptic and video endoscopes used in the examination of the hollow viscera. 2000; Designation F1518-00, West Conshohocken, Pa.