Comparative study on antibiotic resistance profiles and plasmid presence in water samples focusing water bodies of Dhaka City (Hatirjheel & Gulshan Lake)

Abstract

Global concern has been expressed for antibiotic-resistant bacteria (ARB) and their resistant genes. Hotspots of antimicrobial resistance (AMR) have also been reported from aquatic ecosystems of urban areas, especially in fast-growing megacities, i.e., Dhaka, Bangladesh. The purpose of the present study was to compare the prevalence of plasmids and antibiotic resistance patterns of isolates of Salmonella spp., Escherichia coli, and Vibrio cholerae recovered from two urban lakes, Hatirjheel Lake and Gulshan Lake. Systematically, water samples were taken for six months, and selective culture and polymerase chain reaction (PCR) were used to confirm the existence of bacterial isolates. Antibiotic resistance to 14 antibiotics of principal classes was assessed by Kirby-Bauer disk diffusion. Plasmid DNA was extracted to determine if mobile genetic elements of resistance existed. The findings were such that the two lakes had an incredibly high prevalence of multidrug-resistant (MDR) bacteria, and Hatirjheel isolates had much higher levels of resistance. Nearly 70% of the V. cholerae isolates, 65% of Salmonella spp., and 85% of E. coli were resistant to two or more antibiotic classes. Worse yet, 23% of Hatirjheel E. coli isolates and 18% of Gulshan Lake isolates had resistance to last-resort carbapenem antibiotics like imipenem. Plasmid analysis had a strong correlation with resistance patterns. Hatirjheeel strains of E. coli had 80% carriage of plasmids, whereas Gulshan isolates had 60%. Hatirjheeel had high carriage of plasmids in Vibrio cholerae as well as Salmonella spp., supporting environmental factors resulting in horizontal gene exchange as well as transmission of AMR. The findings have implications for wastewater system reforms and the need to harmonize environmental monitoring to limit the spread of AMR in the environment. Urban lakes like Hatirjheel and Gulshan are not only scenic and recreational areas but also areas of high transmission of AMR, which may have direct and indirect effects on the health of the local population. It steers the One Health initiative as a whole towards facilitating intersectoral actions to control antibiotic resistance and provides essential baseline data on the environmental AMR status in Dhaka.