Recent years have seen a worrying increase in reported outbreaks of carbapenem-resistant Enterobacteriaceae (CRE) and other multidrug-resistant (MDR) bacterial infections linked to duodenoscopes. These complex medical instruments, crucial for endoscopic retrograde cholangiopancreatography (ERCP) procedures, have come under scrutiny from the FDA, CDC, and public health bodies due to their intricate design that can hinder effective reprocessing. Numerous studies have highlighted the association between reprocessed duodenoscopes used in ERCP and subsequent MDR bacterial infections, especially those caused by CRE, raising serious concerns about patient safety. Unlike previous endoscope-related infection incidents, these recent outbreaks have occurred despite healthcare facilities adhering to manufacturer guidelines and established professional reprocessing protocols, underscoring a critical gap in current disinfection practices.
The core issue highlighted by these outbreaks is the inadequacy of current reprocessing guidelines to consistently deliver a patient-safe gastrointestinal (GI) endoscope, free from potential pathogens. The safety margin associated with reprocessing these devices appears minimal, if not nonexistent. There are primarily two, possibly three, key reasons for this persistent reprocessing failure and the continued occurrence of outbreaks. Firstly, research indicates that the internal channels of GI endoscopes, including duodenoscopes, can harbor a significant load of enteric microorganisms, ranging from 107 to 1010. While the cleaning phase of endoscope reprocessing achieves a 2- to 6-log10 reduction in microbes, and high-level disinfection (HLD) adds another 4- to 6-log10 reduction against mycobacteria, the overall microbial reduction ranges from 6 to 12-log10. This leaves a minimal to nonexistent margin of safety, ranging from a potential 4-log10 contamination level (maximum contamination, minimal cleaning/HLD) to -5-log10 (minimum contamination, maximum cleaning/HLD). Consequently, any lapse in proper reprocessing, particularly in areas like the elevator channel crevices, can lead to residual contamination and subsequent patient-to-patient pathogen transmission. This narrow safety margin sharply contrasts with the robust 17-log10 safety margin associated with the cleaning and sterilization of standard surgical instruments.
Secondly, GI endoscopes, beyond their high microbial burden (107–1010 bacteria), present a complex architecture characterized by long, narrow channels, sharp turns, and components that are inherently challenging to clean and disinfect, notably the elevator channel. The elevator channel, specific to side-viewing duodenoscopes, is uniquely designed to guide catheters, guidewires, and accessories into the endoscopic field of vision. This channel’s intricate design incorporates crevices that are difficult to access with standard cleaning brushes, potentially hindering effective reprocessing. Accumulating evidence suggests that MDR pathogens are acting as sentinel organisms, indicating a broader failure in reprocessing the complex design features of duodenoscopes, thus posing a significant infection risk to patients undergoing procedures involving these devices.
Thirdly, the formation of biofilms might contribute to reprocessing failures and the ongoing outbreaks related to endoscopes. Biofilms are complex communities of bacteria encased in a matrix of exopolysaccharides, firmly adhering to surfaces. They thrive in moist environments. Prompt reprocessing after use, coupled with thorough drying of the endoscope, minimizes the opportunity for biofilm development. However, biofilm formation within endoscopes during routine clinical practice may be linked to suboptimal reprocessing practices, such as reusing detergent, inadequate manual cleaning, and incomplete drying. While immediate reprocessing, ideally within one hour of use, is recommended, evidence-based guidelines regarding acceptable delays in endoscope reprocessing are currently lacking. The precise contribution of biofilms to endoscope reprocessing failures remains an area of ongoing investigation.
Given the limitations of current reprocessing methods, what immediate steps can be taken to enhance patient safety? Currently, there is no single, universally applicable, and definitively proven technology or strategy that can guarantee complete patient safety in this context. However, rigorous enforcement of evidence-based best practices remains paramount. This includes meticulous equipment maintenance and regular audits, coupled with mandatory competency testing for reprocessing staff at least annually. All personnel involved in duodenoscope reprocessing must possess comprehensive knowledge and training regarding the specific reprocessing instructions for these devices. This training must incorporate recent recommendations, such as the use of smaller bristle cleaning brushes and enhanced flushing and cleaning protocols specifically targeting the duodenoscope elevator channel. While manufacturers have described these enhanced steps as validated, publicly available data confirming their effectiveness in consistently rendering ERCP scopes bacteria-free is still needed. More aggressive measures are likely necessary to prevent further outbreaks. It is recommended that all healthcare facilities reprocessing duodenoscopes adopt one of the enhanced reprocessing methods, prioritized based on their potential to increase the margin of safety. These enhanced methods include: (1) Ethylene oxide (ETO) sterilization following HLD with routine microbiologic surveillance; (2) Double HLD with routine microbiologic surveillance; (3) HLD followed by quarantine of the scope until negative culture results are obtained; (4) Liquid chemical sterilant processing systems using peracetic acid (followed by rinsing with extensively treated potable water) with routine microbiologic surveillance; (5) Other FDA-cleared low-temperature sterilization technologies (provided material compatibility and sterilization validation are confirmed) after HLD, with routine microbiologic surveillance; and (6) HLD with routine microbiologic surveillance. These supplemental measures to improve duodenoscope reprocessing, initially proposed in May-June 2015 and reinforced by the FDA in August 2015, represent crucial steps toward mitigating patient risk. For example, UNC Hospitals has adopted ETO sterilization after HLD, supplemented by double HLD with periodic microbiologic surveillance as a backup when ETO sterilization is unavailable, demonstrating a proactive approach to enhancing patient safety in duodenoscope reprocessing.
