Escherichia coli in water samples at Bhutan's National Food Testing Laboratory: baseline findings and scoping for antimicrobial resistance surveillance

Bhutan has no established system for monitoring antimicrobial resistance (AMR) in waterborne bacteria. Bhutan's National Food Testing Laboratory (NFTL) analyses regulatory, commercial, and private food and water samples and conducts testing for key microorganisms, including Escherichia coli. We analysed NFTL's data to provide a baseline estimate of E. coli in water samples received and the role NFTL could play in AMR surveillance. NFTL tested 186 water samples from Thimphu in 2024 for E. coli, of which 67 (36%) were positive. E. coli was not detected in commercially packaged drinking water, filtered water, or treated water samples, but was present in all stream water (n = 25) and some raw (15/51, 29%) and tap water (27/71, 38%) samples. No seasonal patterns were observed, though sampling was not conducted systematically. There are limited data from Bhutan and low- and middle-income settings on AMR in waterborne bacteria. As Bhutan implements a One Health approach to AMR, establishing AMR surveillance in bacteria from environmental sources requires consideration of the role NFTL could play to complement existing drinking water surveillance. Key questions include which water sources will be included, where additional laboratory techniques will be implemented, and how sampling, methodologies, and data will be standardised.