Contaminated duodenoscopes in ERCP: sensitivity of detection and risk of underdetection

Background and aims: Periodic duodenoscope cultures are essential to timely detect contamination, but their sensitivity remains unknown. This study aims to determine the sensitivity of duodenoscope cultures and to estimate the prevalence of contaminated duodenoscope use.

Methods: We combined duodenoscope microbiologic surveillance data from March 2015 to June 2022 with usage data to evaluate patient exposure to duodenoscopes contaminated with microorganisms of gut or oral origin (MGO). We identified duodenoscopes with repeated species-level contamination within a year and used molecular typing to confirm genetic relatedness. Genetically related microorganisms over multiple duodenoscope cultures of a single duodenoscope indicated a period of sustained contamination, and a cluster was defined as overlapping periods of sustained contamination between different duodenoscopes. If microorganisms were not available for molecular analysis, we marked the period as unconfirmed. A sample was defined as false negative if it did not show the target microorganism(s) in a period of sustained contamination. We used 3 scenarios to hypothesize about contaminated use and culture sensitivity.

Results: We included 556 duodenoscope cultures with 185 (33.3%) contaminated with MGO. The total usage of duodenoscopes was 5226. We identified 1 period of sustained contamination, 6 unconfirmed periods, and 2 clusters. Depending on our scenario assumptions, the percentage of contaminated use varied from 12.3% to 23.7% and culture sensitivity ranged from 82.2% to 98.9%.

Conclusions: Limited sensitivity of duodenoscope cultures leads to improper clearance of duodenoscopes for clinical use, increasing risks of outbreaks. The applicability of a single culture to end a duodenoscope's quarantine should be re-evaluated.