Abstract:Objective To investigate the bacterial contamination of water specimens at different pre-discharge time of flexible endoscopic final rinse water before daily use, and provide reference basis for choosing the optimal pre-discharge time in clinical work. Methods From August to December 2023, the water produced by the purified water equipment of the digestive endoscopy centers of 4 tertiary first-class medical institutions in Jiangxi Province, as well as the final rinsing water at the terminal-point at different pre-discharge times (before pre-discharge, discharge of 1, 3, 5, and 10 minutes) were subjected to on-site sampling,the collected water specimens were performed microbiological cultures by pouring and filter membrane methods, unqualified water specimens were performed bacterial identification. Results 48 specimens of water produced by purified water equipment were collected, with qualified rate of 100%. 480 final water specimens were collected, with a qualified rate of 0 before pre-discharge. The qualified rates of pre-discharge at 1, 3, 5, and 10 minutes were 0, 21.88%, 55.21%, and 73.96%, respectively. Bacterial colony counts in the final rinse water with different pre-discharge times in 4 medical institutions showed statistically significant differences (all P<0.001). As the pre-discharge time increased, bacterial colony counts in the final rinse water of all four medical institutions showed a decreasing trend. The pairwise comparison of the overall bacterial colony count of the final rinse water at different pre-discharge time showed that there was no statistically significant difference in the bacterial colony count of the final rinse water at 5 and 10 minutes of pre-discharge (P>0.05), while the pairwise comparison between other time points showed statistically significant differences (all P<0.001). Environmental contaminated bacteria such as Micrococcus luteus, Cupriavidus paucula, and Sphingomonas paucimobilis were detected from the unqualified water specimens. Conclusion With the extension of pre-discharge time, the degree of bacterial contamination in the final rinse water significantly decreases. All levels of medical institutions need to pre-discharge the final rinse water daily, and the pre-discharge time should last for at least 5 minutes.