Gastroenterological Endoscopy. Группа авторов
Cleaning and disinfection of endoscopes are critical safety and quality tasks that all gastrointestinal endoscopy departments must be attentive to. The soiled environment in which endoscopes are used yields a significant bioburden for cleaning and eradication before their reuse in subsequent patients. The complexity of endoscope design further challenges the task of producing a microbe-free instrument. Our recognition of reprocessing requirements and adoption of standardized approaches to reprocessing developed slowly over several decades.1 The Spaulding criteria for critical instruments, which are those that contact intact but contaminated mucosal membranes, stipulate that reprocessing should achieve, at a minimum, high-level disinfection (HLD). This level of reprocessing eradicates all living bacteria, viruses, and most spores, unless present in high numbers. Current international guidelines for HLD all espouse stepwise processes, which include precleaning at the bedside, thorough submersion and manual cleaning, standardized disinfection by exposure to approved liquid chemical germicides (LCGs) at specific parameters, and followed by rinsing, drying, and appropriate storage. Recent outbreaks of infections subsequent to endoscopic retrograde cholangiopancreatography (ERCP) have been attributed to persistent contamination at the elevator mechanisms, despite appropriate reprocessing. This has prompted interim advice to ensure optimal training and oversight of cleaning staff while intensifying attention to all standard steps of HLD, plus consideration of local benefit of use of double reprocessing cycles, ethylene oxide sterilization after each procedure, adenosine triphosphate (ATP) testing to assay the adequacy of the cleaning phase of reprocessing, and intermittent or per procedure endoscope cultures after full HLD.
Recurring clusters of infections, primarily related to lapses in standard reprocessing steps, have repeatedly focused the attention of the medical community and the broader regulatory and patient communities on the issue of reprocessing. This has culminated in the development of multiple national and international standards and guidelines for reprocessing, from many affiliated medical and technical specialty groups. Despite differences in detail and specificity, most existing guidelines are highly uniform in their requirements.2,3,4,5,6,7
6.2 Principles of Disinfection
6.2.1 Definitions
The language of reprocessing employs numerous terms with varied derivations from both regulatory and scientific origins. Reprocessing refers to a validated process that is used to render a used or soiled medical device fit for a subsequent single use.8 It typically includes steps to remove gross soil by cleaning (or washing), and disinfection or sterilization to inactivate microorganisms. Cleaning is the physical removal of soil and contaminants to minimize transfer from one patient to another or between uses in a single patient. It should enable successful subsequent disinfection or sterilization and prevent accumulation of residual soil throughout the useful life of the product.9 Disinfection is the process that employs physical or chemical means to destroy pathogenic and nonpathogenic microorganisms present on inanimate objects, such as medical devices. Hence, disinfectants are the agents used to destroy the microorganisms. Individual agents are sometimes referred to as germicides, fungicides, sporicides, etc., based on the microorganisms they are designed to inactivate. In contrast, antiseptics are agents that reduce or eliminate microorganisms on skin or in living tissues.
Disinfection is commonly categorized by the degree of clearance of microorganisms: HLD eradicates all bacteria, viruses, and most but not all spores when present in high numbers; intermediate-level disinfection inactivates all bacteria, mycobacteria, and most viruses but not bacterial spores; low-level disinfection destroys most bacteria, viruses, and fungal spores, but some mycobacteria, nonlipid viruses, and bacterial spores remain viable.
Sterilization achieves 100% eradication of all forms of life or infectious agents. This degree of certainty cannot be measured or accurately achieved; hence, sterility is often equated to a very low probability of less than 10–6 (< 1/106 = less than one in a million) of a nonsterile unit following sterilization. This “sterility assurance level” (SAL) is required for injectable medications and medical devices by the Food and Drug Administration (FDA) in the United States.10 HLD is also intended to reduce microbial load to a SAL of 10–6, with the exception that some resistant spore forms are not eradicated.
The intensity of reprocessing for all medical devices is based on the Spaulding classification, which stipulates that the degree of disinfection or sterilization should be based on the risk of transmission, as related to the nature of contact with the patient (
6.2.2 Application to Gastrointestinal Endoscopes
By the Spaulding criteria, gastrointestinal endoscopes require HLD, in accord with their routine exposure to nonsterile mucous membranes. Endoscopes or devices that are used in sterile environments, such as percutaneous laparoscopic passage and insertion via an enterotomy during a laparotomy, are deemed to require sterilization. Devices breaking the mucosal surface, such as needles and biopsy cables, and those entering sterile systems such as the biliary tree or pancreatic ducts, must be sterilized between uses. Many busy endoscopy departments opt for use of sterile single-use accessories such as biopsy cables, sphincterotomes, and biliary guidewires to avoid the expense and organizational processes required for sterilizing inexpensive high-volume devices.
Table 6.2 Steps in reprocessing of flexible endoscopes
| Bedside (point-of-use) precleaning | • Prior to transport to reprocessing room• Manually wipe exterior surfaces with water and enzymatic detergent• Aspirate or flush detergent through air/water and biopsy channels until clear | • Removes visible soil and blood before drying and adherence• Optimally reduces bioburden by 103 |
| Manual washing | • Disassembly, followed by leak testing• Full submersion of entire endoscope• Manual washing and brushing of exterior with enzymatic solution• Brushing and flushing of accessible channels• Thorough water rinse | • Optimally reduces bioburden by 106 |
| High-level disinfection | • Automated preferable to manual• Multiple machines and agents—require compatibility per IFUs• Adhere to IFUs for minimum concentration and contact times | • Optimally reduces bioburden by 106• Narrow margin of safety primarily in complex instruments with elevators |
| Alcohol flushing | • Usually an AER cycle• Rinse of all LCG• Alcohol flush to facilitate removal of water and full drying | • Reduces risk of patient or personnel exposure• Facilitates complete removal of water |
| Forced air drying | • Filtered or “medical” air• Often heated• No fixed time/temperature parameters | • Enhances microbial kill• Prevents moist environment for proliferation of residual organisms during storage |
| Appropriate storage | • Upright, dry, ventilated without exposure to ambient soiled atmosphere | • Ensures clean, patient-ready endoscope at start of next procedure, calendar |
| Abbreviations: AER, automated endoscope reprocessors; IFUs, instructions for use; LCG, liquid chemical germicide. | ||
The most uniformly adopted approach to reprocessing of endoscopes employs several standardized steps (
1.