Occurrence of antibiotic-resistant bacteria in urban surface water sources in Bangladesh

Abstract Infections caused by antibiotic-resistant bacteria (ARB) result in thousands of human deaths annually worldwide. Surface waters are impacted by anthropogenic factors, which contribute to the emergence and spread of ARB in the aquatic environment. There has been a notable lack of study on antibiotic resistance in surface water, particularly in developing nations like Bangladesh, where antibiotics are widely consumed and are not disposed properly. In this study, bacteria strains isolated from three rivers and two lakes in Khulna city, Bangladesh were characterized for their antibiotic resistance using disc diffusion method. Overall, of 56 isolates of bacteria from samples of the surface water sources, most were resistant to Ciprofloxacine (75.0–87.5%) and Ceftriaxone (65.6–78.1%). Ampicillin showed (9.4–18.8%) a comparatively lower resistance rate than that of Ciprofloxacine and Ceftriaxone. The prevalence of ARB was observed to be higher during the wet seasons compared to the dry seasons. The 16S rRNA gene analysis showed that Shigella flexneri was dominant (17.9%) in surface water followed by Escherichia fergusonii (12.5%), Proteus mirabilis (10.7%) and Enterobacter quasihormaechei (8.9%). The genus level analysis showed that Enterobacter (23.5%), Shigella (20.6%), and Escherichia spp (14.7%) were found most abundant both in the rivers and lakes water. The findings of this study underscore the urgent need for routine surveillance of antimicrobial resistance in surface water sources nationwide, as well as the implementation of safe disposal practices for antibiotics utilized in healthcare, animal husbandry, and aquaculture.