A comprehensive surveillance study spanning seven years was conducted at a 1900-bed academic medical center situated in Singapore. The central focus of this study was to unravel any epidemiological connection between the infections in the bloodstream post-procedures and contamination in endoscopes. Interestingly, despite the detection of persistent contamination via routine microbiological surveillance, no such association was identified.
The findings were released for public viewing on 14th May 2026, in the prominent American Journal of Infection Control. It was suggested that endoscopic BSIs, after the procedure, are primarily influenced by the intensity of the procedure and the susceptibility of the patients rather than any potential transmission from the endoscopes themselves.
The data analyzed for the study comprises 316,533 endoscopic procedures carried out over six years, starting from January 2018 until December 2024. A significant number of post-endoscopic BSI incidents were noted at 2,366, resulting in an overall occurrence rate of 7.5 per thousand procedures. The highest BSI rates were observed in Bronchoscopy and ERCP procedures.
Conversely, endoscopies such as gastroscopy, cystoscopy, and colonoscopy were associated with lower rates. The research team explained that these differences in rates might be stemming from factors like the procedure’s invasiveness, disruption of the mucosal layer, concurrent infection, and the underlying susceptibility of the patient rather than any possible implication of the endoscope.
The study was conducted keeping in line with the guidelines set by the Gastroenterological Society of Australia, including routine microbiological surveillance. High-risk endoscopes, including duodenoscopes, bronchoscopes, and cystoscopes, were subjected to monthly microbiological culture testing, while low-risk endoscopes such as gastroscopes and colonoscopes were cultured on a quarterly basis. Throughout the study tenure, 21,899 surveillance cultures were analyzed, yielding 443 positive instances.
The research team did note overlap at the species-level between bloodstream isolates and surveillance cultures, involving organisms such as Escherichia coli, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Candida species. However, no correlation was found between the patients affected and exposure to the implicated endoscope within the designated contamination window. The authors stress that contamination detected through surveillance did not have a definitive correlation with patient harm. Their findings support a low probability of exogenous transmission.
The study also reveals that the contamination detection rate saw a spike post the adoption of sensitive surveillance techniques in 2023, such as membrane filtration-based sampling. A noticeable increase from 1.0% in 2022 to a staggering 12.5% in 2024 was recorded, attributed to enhanced organism recovery rather than decreased reprocessing performance. The study makes it clear that microbiological surveillance should be seen as a tool for monitoring the system and ensuring quality-assurance rather than a parameter for predicting infection risks.
Based on the findings, the institution implemented added measures to mitigate potential risks. With bronchoscopy recording the highest BSI rate, the hospital moved all 21 bronchoscopes to sterilization processing in April 2025. To measure the effectiveness of these measures, ongoing surveillance was also put into place. They concluded their study by stating that the amalgamation of electronic device tracking, clinical outcome monitoring and microbiological surveillance building a rigorous structure ensuring endoscope safety in routine clinical practice.