Environmental isolation, characterization & antimicrobial resistance profiling of klebsiella pneumoniae & acinetobacter baumannii from community wastewater in Dhaka: a comparative analysis

Abstract

Environmental antimicrobial resistance has become a growing global health concern, where community wastewater plays a critical role in the accumulation, persistence, and distribution of the resistant pathogens. This study focuses on investigating the environmental occurrence, phenotypic and molecular characterization, and antimicrobial resistance profiling of Klebsiella pneumoniae and Acinetobacter baumannii isolated from the community wastewater in multiple areas of Dhaka, Bangladesh, along with emphasizing the presence of potential co-existence of these organisms with associated resistance dynamics. The community wastewater samples were collected from different areas of Dhaka city and processed using culture-based isolation. Afterwards, the phenotypic identification and molecular characterization provided a validated species identification. Importantly, Antimicrobial susceptibility testing (AST) was performed to identify the resistance intensity and potential risk across these isolates. Moreover, 45 isolates of Klebsiella pneumoniae and 41 isolates of Acinetobacter baumannii were isolated and characterized from 32 samples of community wastewater, resulting in the highest co-dominance in the Mohammadpur area of Dhaka with 47.6% Klebsiella pneumoniae and 52.4% Acinetobacter baumannii prevalence. Besides, both organisms were frequently isolated with mixed colonies, indicating their co-existence across all sampling sites. Further, AST of mixed colonies exhibited an extreme resistance with 90% isolates with MAR index 1.0, and more the 90% isolates showed MAR index >0.2, indicating high antibiotic selective pressure in comparison to the resistance profile of Klebsiella pneumoniae and Acinetobacter baumannii, respectively. These findings highlight the Dhaka community wastewater as a high-risk AMR contamination site and co-existing pathogens promoting resistance dissemination and amplification via horizontal gene transfer and biofilm-mediated interactions, suggesting a critical need for integrated environmental surveillance and strategies to control the increasing antimicrobial resistance.