Duodenoscope-associated infections: risks and countermeasures

The exact number of endoscopic retrograde cholangiopancreatography (ERCP) procedures performed worldwide each year is not known; the estimate for the United States is up to 700 000 cases. The high case volume implies that even infrequent adverse events are clinically and economically relevant. These events include procedure-related infections, which occur in 0.5 %–3 % of cases [1]. Such infections are likely to be predominantly induced endogenously by translocation of oral or intestinal bacteria. The extent to which infections are caused by exogenous bacteria is not well known, as these are rarely considered in clinical practice. However, recent reports on outbreaks of duodenoscope-associated infections (DAIs) have led to an increased awareness of this device-related risk. Most of these outbreaks were caused by multidrug-resistant organisms (MDROs) transmitted through contaminated duodenoscopes as proven by molecular typing. Such organisms can cause serious and life-threatening infections.

Until recently, only reusable duodenoscopes could be used for ERCP. Optimal cleaning, disinfection, and even more so sterilization, are difficult because of the complex mechanical features incorporated into the distal tip of the device. A recent postmarket surveillance report on culturing results showed that up to 5.4 % of properly collected samples from reprocessed duodenoscopes tested positive for organisms of high concern [2]. Supplemental measures such as routine or periodic microbiologic culturing of duodenoscopes and reprocessing with repeat high-level disinfection (HLD), ethylene oxide sterilization after HLD, or liquid chemical sterilization (LCS) have been recommended. HLD and LCS were recently compared in a prospective randomized study including 878 post-reprocessing surveillance cultures performed in a high-volume center. Cultures were positive for any organism in 1.9 % of cases, with no significant difference between the two methods [3]. Although the culture positivity rate is low, the study results indicate that even the best manual cleaning protocol applied cannot achieve eradication of all potential pathogens and eliminate the potential for human error. A first nationwide study recently showed a high prevalence rate of digestive bacteria in duodenoscopes in the Netherlands. Overall, 92 % of the 73 national centers sampled 745 sites of 155 duodenoscopes from three distinct manufacturers. In more than one third of the participating institutions, at least one patient-ready duodenoscope was identified as contaminated. Furthermore, 15 % of the duodenoscopes harbored microorganisms that indicated residual organic material from previous patients. Contamination occurred with all types of duodenoscopes [4].

The procedural risk of developing infections with different degrees of severity related to contaminated duodenoscopes has so far been rated as very low. A historical 1993 position paper from the American Society for Gastrointestinal Endoscopy (ASGE) suggested a prevalence of 1 in 1.8 million endoscopies [5]. No risk calculation specifically for DAIs has been reported; however, data are urgently needed for strategic planning of DAI prevention.

“What emerges from this study and other recent reports on duodenoscope-associated colonizations and infections is that there is a low but not negligible risk of performing an ERCP with a contaminated reusable duodenoscope.”

In this issue of Endoscopy, Kwakman et al. report on risk evaluation of DAIs in the Netherlands [6]. The authors identified all DAI outbreaks that were reported in their country between 2008 and 2018. Cross-contaminations of the reported cases were confirmed by molecular matching of patient and duodenoscope cultures. The risk ratios for DAIs were calculated by the number of cases related to the number of ERCPs performed during the study period according to Dutch Hospital Data. The results revealed three outbreaks with 21 DAIs and 52 cases of duodenoscope-associated colonizations (DACs). All outbreaks involved the spread of MDROs. The results of this well-performed study demonstrated a minimum calculated risk for DAI of 0.01 % corresponding to one MDRO infection in approximately every 10 000 ERCP procedures. The risk of DAC is more difficult to determine because reports on asymptomatic cases that were colonized are limited. Taking this into account, a minimum risk of one DAC per 4000 procedures was calculated. Approximately one third of patients who underwent ERCP with a contaminated duodenoscope developed DAIs. These findings correspond to the “attack rates” of between 15 % and 41 % reported from other outbreaks.

The results of the study are important in several respects. The minimum risk of DAIs related to MDROs is substantially higher than previously reported. The authors emphasize that the actual risk is most probably even higher for several reasons. It is not known to what extent DAIs remain undetected and whether all identified cases are reported. In addition, suspected DAIs may erroneously not be confirmed because of false-negative cultures from contaminated duodenoscopes. We know even less about the incidence of non-MDRO DAIs with exogeneous sensitive bacterium; these cannot be differentiated from endogenous infections in daily practice.

What emerges from this study and other recent reports on DACs and DAIs is that there is a low but not negligible risk of performing an ERCP with a contaminated reusable duodenoscope, even after optimized reprocessing and with knowledge of the problem. Recently introduced duodenoscopes with disposable endcaps or protection devices facilitate cleaning and disinfection of the complex distal end. However, the impact on contamination rates and the procedural performance remains to be proven in ongoing studies. It should be considered that most residual bacterial contamination occurs in the region of the elevator, but it can also be identified in the instrument channel, which may be exposed to damage, shredding, moisture, and biofilm formation.

Health care providers must decide the extent to which the risks of DAI can be balanced against the benefits of ERCP. Complete elimination of risk would require transition to single-use duodenoscopes. The advantages, however, must also be weighed against the costs of the devices, which for reusable endoscopes include their maintenance, reprocessing, and supplemental measures. The environmental impact of endoscope disposal after use must also be taken into account. The concept of disposable duodenoscopes will additionally depend on case volume and infection rates in individual institutions, as well as the functionality of these new devices, which should be noninferior to traditional endoscopes [7]. At present, the use of single-use devices should be considered in selected patients with increased risk for a severe course of DAI [8]. The study of Kwakman et al. expands our knowledge and awareness of ERCP-related infections and provides information for the future developments required to resolve the problem, such as improving the reprocessing methods and microbial surveillance strategies, increasing awareness about the clinical impact of DAIs, and the need for ongoing incentives for research and development of new cost-effective technologies.

Publication History

Article published online:
19 August 2021

• References

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