Discussion

This study evaluated the utility of an institutional endoscope surveillance culture program by examining postreprocessing contamination and CRO match rates across four commonly used gastrointestinal scope types. EGD demonstrated the highest overall positivity rate at 25.9%, whereas EUS exhibited the highest rate of matching to patient isolates at 33.3%. Although ERCP scopes are widely recognized as high-risk for contamination due to their complex duodenoscope design, our findings underscore that other scope types, such as EGD and EUS, may also harbor clinically significant contamination despite adherence to IFU-based reprocessing protocols. Overall, matched CRO isolates were identified in 5% (3 of 61) of positive cultures obtained following initial reprocessing.

The literature on endoscope-associated infections (EAIs) has predominantly focused on ERCP procedures, in part due to well-documented challenges with duodenoscope reprocessing. ^{Reference Neves, da Silva, Ventura, Cortes, Duarte and de Souza7} A meta-analysis reported a 15.25% contamination rate among reprocessed duodenoscopes. ^{Reference Larsen, Russell and Ockert8} In our study, ERCP scope positivity rates were lower than the rates for EGD scopes. These findings suggest that limiting surveillance efforts to ERCP alone may overlook contamination risks associated with other gastrointestinal endoscopes. Differences in surveillance frequency across scope types may have influenced observed positivity rates. ERCP scopes underwent routine weekly surveillance, whereas other scope types were primarily cultured during CRO investigations. Additionally, increased institutional awareness surrounding duodenoscope-associated infections may have resulted in more rigorous reprocessing oversight for ERCP scopes compared to other devices. ^{Reference Chen, Liu, Lai, Chang and Yen9}

Several factors likely contribute to the observed variation in contamination rates. These include scope design complexity, differences in manual cleaning techniques among technicians, variability in automated endoscope reprocessor performance, and environmental conditions affecting scope drying, storage, and transport. ^{Reference Neves, da Silva, Ventura, Cortes, Duarte and de Souza7} While our institution maintained adherence to IFU and internal protocols, unmeasured deviations in practice or equipment may have contributed to residual contamination. Additionally, the possibility of contamination during postreprocessing handling or storage—both of which occur in non-sterile environments—cannot be excluded.

Although the match rate between contaminated scopes and patient isolates was low across most scope types, the presence of CROs on reprocessed endoscopes remains clinically meaningful. The detection of such organisms, even in the absence of direct transmission, indicates a breach in disinfection integrity and a potential risk to future patients. A previously published review estimated that composite EAI rates following gastrointestinal procedures were approximately 0.2%, with higher rates following ERCP (0.8%), followed by upper GI endoscopy (0.123%) and lower GI endoscopy (0.073%). ^{Reference Perisetti, Tharian, Tham and Goyal10} While these rates are relatively low, they translate into substantial absolute numbers given the volume of procedures performed nationwide.

At our institution, any scope found to be contaminated with concerning organisms underwent immediate reprocessing and was quarantined until clearance. If repeat cultures remained positive, the scope was returned to the manufacturer for further inspection, in accordance with Food and Drug Administration (FDA) recommendations. The FDA has increasingly advocated for the adoption of disposable or partially disposable endoscope components in response to persistent contamination and EAIs. ¹¹ However, the routine use of disposable devices remains limited due to their high cost, environmental burden, and lack of availability across all scope types. Consequently, routine surveillance cultures may serve as an effective intermediary solution to identify contamination and prevent patient harm.

This study has several limitations. First, we did not assess patient transmission events, as contaminated scopes were not reused before undergoing repeat reprocessing. Second, the manual cleaning phase was not systematically audited, which could contribute to unrecognized variability in scope decontamination. Third, postreprocessing contamination during transport or storage could not be definitively excluded. Lastly, the study was conducted at a single academic center with specific workflows and equipment, which may limit generalizability to other institutions.

While postreprocessing contamination was observed across multiple scope types, CRO matches were uncommon. However, we did not systematically evaluate patient transmission events, limiting conclusions regarding the clinical impact of contamination. Given the low match rate observed in this single-center study, universal surveillance culturing may not be warranted across all settings. A risk-based or targeted surveillance strategy may be more appropriate, particularly for higher-risk scope types or in institutions with endemic multidrug-resistant organisms.