PhD defence K. (Koen) van der Ploeg

Below is a brief summary of the dissertation:

Endoscopes are essential for the diagnosis and treatment of gastrointestinal conditions but also pose a potential risk of contamination and infection. This thesis examines the frequency, causes, risks, and potential solutions for endoscope contamination, aiming to improve patient safety.

International outbreaks have shown that particularly duodenoscopes, used in endoscopic retrograde cholangiopancreatography (ERCP) procedures, can become contaminated and transmit pathogens. This thesis demonstrates that infections from contaminated duodenoscopes also occur outside of outbreak situations. The risk appears low (<0.9%), but these infections are difficult to recognize, necessitating further research.

Additionally, the prevalence of multidrug-resistant organisms (MDROs) among ERCP patients was investigated, which is about 11% in the Netherlands. However, the reliability of rectal swabs as a screening method proved to be limited. The presence of MDROs in the duodenum was therefore overestimated, potentially leading to unnecessary preventive measures.

The frequency of duodenoscope contamination with oral or gastrointestinal flora ranged from 14% to 48% in retrospective analyses and was 21% in a prospective study. The biopsy and suction channels were the most frequently contaminated. The duration of manual pre-cleaning was found to be important, with manual cleaning times shorter than five minutes significantly increasing the risk of contamination. Interventions such as the introduction of a new endoscope cleaning brush (Endoss Push and Pull) and an automatic water-based cleaning system (Aquatyphoon) reduced contamination frequency.

Finally, this thesis shows that culture methods are not always reliable, and contamination of duodenoscopes sometimes goes unnoticed. Biofilm plays a central role in this process. An innovative mass spectrometric method is described as a potential future technique for biofilm detection in endoscopes.