Linear echoendoscopes may pose as big an infection risk as duodenoscopes used for endoscopic retrograde cholangiopancreatography, according to a new real-world study by researchers at the University of Pittsburgh.
Few studies have directly compared contamination rates of linear echoendoscopes with ERCP duodenoscopes, according to the researchers. The new study went a step further and characterized the contamination risk of each type of scope under different reprocessing conditions (Infect Control Hosp Epidemiol 2023;44[9]:1485-1489).
The team evaluated samples from 127 linear echoendoscopes and duodenoscopes that were reprocessed at the University of Pittsburgh Medical Center (UPMC) during a 15-month period. Partway through the study, the hospital had a planned shutdown of equipment for maintenance, so the scopes went from their standard reprocessing with high-level disinfection (HLD) and ethylene oxide gas sterilization to reprocessing with double HLD for a one-month period. Overall, ethylene oxide sterilization was used to reprocess 63% of samples and double HLD was used for the rest. During the study period, UPMC also started to use disposable tips on duodenoscopes, which allowed the researchers to compare contamination rates before and after the switch to disposable tips.
Small Differences
To collect samples, the team swabbed both the channels and elevator mechanisms of each scope. If at least one of these swabs came back positive for pathogens, the scope was considered positive for contamination. Of the 127 samples, 45 (35.4%) were taken from linear echoendoscopes and 82 (64.6%) from duodenoscopes, 27 (21.3%) of which had disposable tips.
Overall, six of 127 samples (4.72%) contained pathogenic contamination. Although the investigators found that ethylene oxide gas sterilization was associated with a numerically lower infection rate than double HLD, the difference was not statistically significant (ethylene oxide, 2.5% vs. double HLD, 8.5%; ethylene oxide risk ratio [RR], 0.29; 95% CI, 0.06-1.54; P=0.12). They also found that linear echoendoscopes had a numerically but not statistically higher contamination rate than duodenoscopes—8.9% compared with 2.4% (RR, 3.64; 95% CI, 0.69-19.1; P=0.10).
Linear echoendoscopes reprocessed with double HLD had the highest risk for contamination (2/18; 11.1%). None of the 53 duodenoscopes reprocessed with ethylene oxide gas sterilization nor the 27 with a disposable tip contained contamination after reprocessing.
The most common bacterial pathogens were Klebsiella pneumoniae, Pantoea species and Staphylococcus aureus. In addition, the investigators also noted that small amounts of fungi species were present. A Candida species was found in 6.4% of cultured endoscopes, which led the researchers to include fungi in microbial scope surveillance.
Although the study was small, primary investigator Ashley Ayres, MBA, BS, CIC, said the findings indicate that “linear echoendoscopes represent a contamination rate similar to ERCP duodenoscopes and should be part of a microbiological surveillance program.” The elevator mechanism in linear echoendoscopes is likely what puts them on par with ERCP duodenoscopes for infection risk, said Ms. Ayres, the director of infection prevention at UPMC. This finding adds to a growing body of evidence showing linear echoendoscopes present a substantial risk for contamination she told GEN Priority Report, noting that a prospective study published in 2017 showed similar results (Gastrointest Endosc 2017;85[2]:390-397.e1).
According to Aaron Preston, RN, BSN, CIC, the senior infection prevention coordinator at Emory University Hospital Midtown, in Atlanta, the findings were not surprising, but the research emphasizes the importance of following each cleaning step closely and using manual techniques, rather than focusing on the overall method used.
“More is not always better,” said Mr. Preston, who was not involved with the new study. “A lot of departments focus on the type or frequency” of their HLD, Mr. Preston said, but the Association for the Advancement of Medical Instrumentation recommends “a quality program that looks at key performance indicators for precleaning, cleaning, drying, storage and [HLD].”
No Perfect Solution
The intensive reprocessing practices required for lumened endoscopes makes reprocessing vulnerable to missed or incomplete steps, Ms. Ayers said. It might not make sense to choose ethylene oxide gas instead of double HLD if there is not an overwhelming disinfection benefit. “Potential safety concerns, costs and processing time may all disfavor ethylene oxide gas sterilization if it does not significantly reduce contamination rates compared to double high-level disinfection,” she said.
For now, a perfect solution doesn’t exist, she added. “The only way to 100% protect against possible contamination of endoscopes would be to move to a fully disposable model, but these models may remain cost-prohibitive and may not yet be sufficient for all clinical applications,” Ms. Ayers said, adding that disposable equipment in healthcare goes against sustainability objectives.
—Kaitlin Sullivan
Ms. Ayers and Mr. Preston reported no relevant financial disclosures.
This article is from the December 2023 Priority Report print issue.