Contaminated duodenoscopes have caused multiple outbreaks of multidrug-resistant infections with sometimes lethal consequences; until these instruments become easier to clean, personnel must strictly follow recommendations for sterilization, surveillance, and unit-by-unit quality control, according to an extensive commentary accompanying an American Gastroenterological Association Clinical Practice Update.
“Patients and physicians want and expect no transmission of infections by any medical instrument,” wrote Bret Petersen, M.D., of the Mayo Clinic, Rochester, Minn., Johannes Koch, M.D., of Virginia Mason Medical Center, Seattle, and Gregory Ginsberg, M.D., of the University of Pennsylvania, Philadelphia. It is the collective responsibility of endoscope manufacturers, health systems, and providers to ensure endoscope reprocessing is mistake proof, establishing systems to identify and eliminate the risk of infection for patients undergoing flexible endoscopy.”
©CDC/James Archer
More than 650,000 endoscopic retrograde cholangiopancreatographies (ERCPs) occur in the United States annually, and “even the lowest reported defect rate of 0.7% will expose 4,500 patients to a preventable risk,” the experts noted. Carbapenem-resistant Enterobacteriaceae (CRE) are becoming more prevalent and have been transmitted during ERCP, even when personnel seem to have followed sterilization protocols to the letter. Clinical CRE infections have a fatality rate of at least 50%, months may elapse between exposure and symptom onset, and infections may involve distant organs. These factors, along with the phenomenon of “silent carriers,” have linked duodenoscopes to at least 250 multidrug-resistant infections and at least 20 fatalities worldwide, the experts wrote (Gastroenterology 2016 May 27. doi: 10.1053/j.gastro.2016.05.040).
Current duodenoscopes can be tough to sterilize. Between 1 billion and 1 trillion organisms typically cover a used instrument. Bedside cleaning cuts this number about 1,000-fold, and manual washing kills about another million organisms, leaving up to 1 billion bugs to be killed by high-level disinfection. That’s “a tall order” that can strain space, time, and staffing resources, especially given the fact that duodenoscopes have “tight crevices and mechanical joints that are exposed repeatedly to highly infectious bioburden,” the experts wrote. Furthermore, slips in processing enable the formation of biofilms that resist both cleaning and high-level disinfection.
The key to stopping duodenoscopes from transmitting dangerous pathogens is manual cleaning, including wiping the outside of the duodenoscope, flushing its channels, and brushing the elevator lever “immediately after use and before the surfaces have become dried,” the experts stressed. Disinfectants should be used at the right concentration and temperature, and for the intended amount of time. Biofilms form on moist surfaces only, so channels should be flushed with alcohol (a desiccant), dried with forced air, and stored in a dry environment.
But recent outbreaks spurred the Food and Drug Administration to recommend further steps – including better oversight and training of reprocessing staff and closer attention to precleaning, manual cleaning, and manufacturer recommendations for use, including determining whether the company used its own “proprietary” cleaning brushes in its validation studies, the experts noted. “Optional supplemental measures” include surveillance cultures of duodenoscopes, ethylene oxide sterilization, and double reprocessing, in which each scope undergoes two cycles of manual cleaning and high-intensity sterilization between patients. Double reprocessing might be the simplest and most easily adopted of these measures, the experts said. The AGA, for its part, recommends active surveillance of patients who undergo ERCP, surveillance cultures of scopes, and recording of the serial number of every scope used in every procedure.
Surveillance culture makes sense, but can be costly and hard to conduct and interpret because sampling detects vast numbers of nonpathogenic organisms in addition to any pathogens, the experts noted. The Centers for Disease Control and Prevention recommends that each institution follow its own complex outbreak sampling protocol and quarantine duodenoscopes for 2-3 days, pending negative results. That may mean buying more duodenoscopes. A less costly option is to culture a subset of scopes at the end of every workweek, the experts said. Real-time tests that reliably reflect bacterial culture results remain “elusive,” but testing for adenosine triphosphate after manual washing is easiest and best studied, they added.
Clearly, industry is responsible for making endoscopes that can be reliably disinfected. “Recent submissions by all three manufacturers (Olympus, Pentax, and Fujinon) have validated current reprocessing outcomes in test environments, and the FDA has ruled that postmarket studies of reprocessing in clinical settings are expected, but these results will not be forthcoming for several years,” the experts wrote. Redesigning duodenoscopes may be “the ultimate solution,” but in the meantime, endoscopists should carefully review indications for ERCP and ensure thorough informed consent. Doing so “will uphold the trust that we must achieve and maintain with our patients,” the authors said.