Antibiotic resistance of bacteria isolated from microbiological control of gastrointestinal endoscopes

Numerous infections and outbreaks linked to insufficient disinfection of thermosensitive endoscopes have been reported in recent years. The effectiveness of endoscope reprocessing is typically monitored via microbiological controls that detect indicator microorganisms. Resistance profile is rarely assessed in routine surveillance of indicator isolates.

To evaluate antibiotic resistance among indicator bacteria isolated from routine surveillance samples of gastrointestinal endoscopes and to determine risk factors for endoscopes' contamination.

Antibiograms were performed on all indicator bacteria recovered from control samples of digestive endoscopes at Brest university hospital between 2016 and 2024. A multivariable regression model was done to identify risk factor for contamination.

During the study period, 99 distinct indicator bacteria were recovered from 65 endoscope controls. Overall, 15.2% of isolates exhibited acquired antibiotic resistance. Among 41 Pseudomonas aeruginosa isolates, 3 were resistant to third-generation cephalosporins, 6 to carbapenems, and 5 to quinolones. Of 54 Enterobacterales isolates, 17 resisted third-generation cephalosporins (including 6 ESBL producers), 12 were resistant to aminoglycosides, and 12 to quinolones. No carbapenemase-producing Enterobacterales were identified. One of three Enterococcus spp. isolates was resistant to amoxicillin. Risk for endoscopes' contamination significantly increased with age of device.

This study is the first to evaluate resistance profiles of indicator bacteria isolated from gastrointestinal endoscopes during regular microbiological surveillance. It highlights the potential role of inadequate disinfection in the cross-transmission of antibiotic-resistant bacteria during endoscopic procedures.