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Determining the best method for assessing microbiological contamination on flexible endoscopes without a working channel: a pilot study

Year: 2025

Type: article

Abstract: BACKGROUND: Flexible endoscopes (FEs) without a working channel can become extensively contaminated. Adequate reprocessing is critical and the quality of these processes can be verified by microbiological sampling. This study aimed to determine the ability to detect colony-forming units (CFUs) after sampling used FEs without a working channel for four different sampling techniques. METHODS: FEs without a working channel were collected after clinical use. Manual pre-cleaning with tap water was performed. A sample was collected from the distal 8-10 cm and tip of the FE by one of four sampling techniques: rolling over a Trypticase Soy Agar with tween and lecithin plate (group 1), rolling over a Plate Count Agar + additives (group 2), swab technique (group 3) or broth technique (group 4). After incubation, a CFU count was performed to assess microbiological contamination. RESULTS: 160 FEs without a working channel were evenly distributed among the four sampling groups. The CFUs on the FEs were classified into four groups: 0 CFUs, 1-50 CFUs, 50-500 CFUs and > 500 CFUs. All four sampling techniques showed a variable number of CFUs, ranging from 0 to uncountable CFUs (i.e., >500) (p ≤0.001). No statistically significant difference was found in how often >0 CFUs were found between the sampling techniques (p = 0.21). CONCLUSIONS: All four sampling techniques were able to detect CFUs on used FEs without a working channel, indicating all four sampling techniques can be used for assessing microbiological contamination.

Source: Journal of Microbiological Methods

DOI: 10.1016/j.mimet.2025.107328