Antimicrobial resistance in Enterobacteriaceae across the human-animal-environment interface at the lower catchment area of Akaki River, Ethiopia

BACKGROUND: The lower catchment area of the Akaki River is characterized by irrigation practices utilizing the Akaki River water and rearing of diverse animal species. Although the One Health approach acknowledges the interconnections among these domains that contribute to the rapid spread of antimicrobial-resistance (AMR), there is a lack of integrated, cross-domain research in this area. Consequently, this study aimed to determine the magnitude of antibiotic-resistant Enterobacteriaceae across the human-animal-environment interface. METHOD: A cross-sectional study was conducted from April 2023 to October 2024 in the lower catchment area of the Akaki River in Ethiopia, to investigate the presence of AMR Enterobacteriaceae across the human- animal-water interface. The study analyzed a total of 720 samples, comprising 700 stool samples (350 from humans and 350 from animals) and 20 water samples. MacConkey Agar was used for the isolation of Enterobacteriaceae, followed by standard biochemical tests and Matrix-Assisted Laser Desorption Ionization-Time of Flight (MALDI -TOF) for the identification. Antimicrobial susceptibility testing (AST) was performed using the disk diffusion method for all isolates against 24 different antibiotics along with two additional antibiotics specifically for Salmonella, and data analysis was performed using SPSS statistical software. RESULTS: Of 1,042 identified Enterobacteriaceae isolates, E. coli was the most prevalent, followed by Providencia alkalifaciens, Citrobacter diversus, Salmonella group A, and Klebsiella oxytoca. The highest level of antibiotic resistance was observed against ampicillin in isolates from both human and animal stool samples. Among water isolates, resistance was highest against cefuroxime, followed by cefazolin. Notably, 62.7% of the isolates were multidrug-resistant (MDR), with a higher prevalence observed in water samples, including resistance against Ertapenem - which highlights a critical public health threat. CONCLUSIONS: The findings indicate the widespread presence of antibiotic-resistant Enterobacteriaceae across the human-animal-environment interface. These results emphasize the urgent need for effective antibiotic stewardship, wastewater treatment, and integrated surveillance of the transmission dynamics of multidrug-resistant bacteria.