Duodenoscope Reprocessing

Background

The pathogenic transmission potential for duodenoscopes has been a well-documented problem since the inception of ERCP, primarily because of the cantilevered elevator mechanism that confers the endoscope's utility within the pancreaticobiliary system. This innately complex endoscope is difficult to clean, with a design precluding autoclave-based heat sterilization or high-temperature steam treatment. Although manufacturers are required to demonstrate that endorsed protocols result in a 6-log ₁₀ reduction in mycobacterium, which serves as a “surrogate marker for elimination of the risk of scope-to-person transmission of infectious agents,” such accelerated failure testing may be insufficient, as multiple recent outbreaks have occurred in spite of adherence to published protocol standards. Overall rates of endoscope-transmitted infections remain very low, with one retrospective study reporting 1.8 nosocomial infections per 1 million procedures performed, although this is considered an underestimate. Historical accounts of endoscope-transmitted infections are notable for unifying threads of reprocessing errors or noncompliance with manufacturer processing protocols and failures of automated endoscope reprocessors. Also noted are issues with failures by personnel to comply with recommended strict manual reprocessing measures.

History of MDRO in Endoscopy

The early North American outbreaks of ERCP-related carbapenem-resistant Enterobacteriaceae (CRE) were attributed to breaches in protocol of high-level disinfection (HLD) and insufficient manual cleaning. Endoscopy-related infections are neither novel nor unanticipated but rather an unfortunate reflection of the endoscope's complex design, heavy utilization, and intolerance to high-temperature sterilization. The organisms associated with nosocomial infections are primarily enteric gram-negative bacteria, though there have been transmitted cases of hepatitis B (1983) and hepatitis C viruses (1997). Additionally, some bacterial species are prone to forming biofilms, a feature that further complicates the HLD process.

In 2012, serial outbreaks of CRE and other MDRO infections emerged despite proper reprocessing techniques and compliance with manufacturer recommendations. The incidences of MDRO infections were likely underreported because of difficulty in identifying outbreaks, given that many of the U.S.-based cases were characterized by unique antibiotic resistance patterns and clonality of bacteria found only by using polymerase chain reaction (PCR). Outbreak sites were typically large, well-resourced medical centers with higher-volume endoscopy centers. Furthermore, county and state health departments assisted certain large urban centers with their investigations into outbreaks of clonally related MDRO (e.g., Seattle and Los Angeles). It is plausible that smaller sites without sophisticated resources would not have detected even a small series of patients infected.

Investigators from Erasmus hospital in the Netherlands were among the first to report this phenomenon, describing infections from a VIM-2–producing Pseudomonas aeruginosa after the introduction of the TJF-Q180V duodenoscope developed by Olympus Corporation in 2010. Thirty patients were infected, with 22 of these cases singularly attributed to a newly introduced duodenoscope. After an exhaustive investigation, including dissection of the new endoscope using electron microscopy, the culprit duodenoscope was withdrawn from use and rates of infectious adverse events returned to baseline.

Subsequently, multiple medical centers published serial cases of patients infected with MDRO, including CRE, with a total of 19 U.S.-based outbreaks reported to date. Outbreaks occurred in high-volume ERCP centers without identifiable lapses in reprocessing. The hospitals typically confirmed clonal relatedness of the organism using PCR, verifying that the likely mechanism of infection originated from a common source, and culprit endoscopes were usually identified in each outbreak. To date, outbreaks have been documented with endoscopes produced by each of the three major manufacturers of commercially available duodenoscopes—namely, Olympus, Fujifilm, and Pentax.

In 2012, a Seattle-based high-volume endoscopy center discovered a carbapenem-susceptible Escherichia coli with a unique resistance mechanism (hyperproduction of AmpC/HAC plus a porin mutation) during participation in a voluntary, statewide surveillance initiative. Between October 2012 and November 2013, 1149 ERCPs were performed, and 32 cases of infection were reported. A collaborative investigation was undertaken between the medical center, city, and state public health departments and the Centers for Disease Control and Prevention. In 7 of the 32 cases “acute case deaths” occurred, defined as death occurring within the same hospital admission and within 30 days of isolate collection. Significantly higher rates of malignancy were noted among those deceased ( p = 0.01), and carbapenem-resistant strains of AmpC E. coli had a greater mortality risk than did infection with carbapenem-susceptible strains ( p = 0.004). The institutional investigation revealed negative environmental cultures, with cleaning practices exceeding manufacturer's reprocessing guidelines. Two duodenoscopes were identified as vectors for the AmpC-producing E. coli, and using pulsed-field gel electrophoresis, clonality was confirmed identifying the pathogen's origins from the suspect devices. All duodenoscopes were submitted for manufacturer's inspection, and four of the eight endoscopes were found to have critical damage, although all were without any sign of operational defects. Such reports of occult mechanical defects are the reason to consider routine endoscopic maintenance and servicing, because critical damages may harbor infectious nidi.

As the result of these findings, the medical center implemented an overhaul of the endoscope reprocessing area and instituted a culture and quarantine process for all duodenoscopes, necessitating the purchase of 20 additional duodenoscopes. Ergonomic changes to scope reprocessing facilities were enacted to minimize worker fatigue and error, and other infection prevention measures—such as provider staff education, skill task alignment (periprocedural handling of endoscope by skilled technicians only), and routine endoscope maintenance checks—were mandated. Separate informed consent forms for duodenoscope use were implemented to increase patient awareness of procedural risks associated with duodenoscope use. All patients undergoing ERCP underwent screening bile and perianal cultures for MDRO. In total, instituting a method of culture and quarantine with HLD, making procedural changes, and adding a 1.0 full-time equivalent microbiology laboratory employee were achieved at a cost of $1 million to meet high ERCP volumes.

After introducing the per-procedure culture and quarantine process, the Seattle-based center evaluated culture data from >2500 swab cultures collected from duodenoscopes. Twenty-nine tested positive for pathogenic bacteria ( Acinetobacter, Enterococcus, E. coli, Enterobacter, Pseudomonas sp.); however, no subsequent infections were detected. Culture results were stratified into two classes of high-concern and low-concern organisms with requisite repeat reprocessing until negative for high-concern organisms. High-concern organisms were defined by Centers for Disease Control and Prevention (CDC) surveillance protocols as noncontaminant, pathogenic microbes such as Staphylococcus aureus, Streptococcus viridans, Enterococcus, and other pathogenic enteric gram-negative organisms. In contrast, low-concern organisms carry a lower pathogenic potential and, when cultured from endoscopes, are usually regarded as contaminants. Endoscopes were not used until culture results returned. As previously discussed, these modifications required additional resources allocated to the microbiology laboratory, endoscopy staff training, and an increase in the number of duodenoscopes available for rotation. Despite the thorough overhaul of institutional, engineering, and personnel controls, an HLD defect rate was defined at 1.9% based on initial year testing. The 20-month aggregate HLD rate (36 total positive cultures) for high-concern organisms ultimately yielded an HLD defect rate of 1.3%.