Antibiotic resistance in enteric bacteria isolated from different water bodies inside Dhaka City

Abstract

There is growing evidence that surface water bodies are important environmental reservoirs of antibiotic-resistant bacteria, and antimicrobial resistance (AMR) is a global public health concern. The antibiotic resistance in pathogenic enteric bacteria that grow in surface water sources in Dhaka Metropolitan City has been examined in this study. Water samples with varied degrees of anthropogenic impact were collected from June 2025 to November 2025 in order to determine the contribution of anthropogenic interference to the waters of four urban water bodies: Hatirjheel, Dhanmondi Lake, Aftabnagar, and Ramna Lake. The study focused on one therapeutically and ecologically significant bacteria: Escherichia coli. Antibiotic susceptibility testing was carried out to determine the profiles of resistance, and isolation was carried out using selective and differential medium (EMB). Polymerase chain reaction (PCR) was used for molecular validation, and plasmid isolation was used to determine the genetic basis of resistance. Agarose gel electrophoresis was used to evaluate PCR amplicons and plasmid DNA, enabling the correlation study between the observed resistance patterns. According to the findings, the incidence of PCR-confirmed antibiotic-resistant isolates was relatively low in Ramna Lake but quite high in Hatirjheel, Aftabnagar, and Dhanmondi Lake. The significance of plasmid-mediated horizontal gene transfer in water was highlighted by the strong association found between the presence of plasmids and multidrug resistance.