Detection and assessment of antimicrobial resistance promotion risk in the Little Akaki River wastewater

The misuse of antimicrobial agents in healthcare and animal farming has led to their release into the environment through wastewater, contributing to the emergence of resistant bacteria. This study analyzed selected antimicrobial concentration and antimicrobial resistance (AMR) risk in the Little Akaki River wastewater. Samples collected from March to December 2019, June 2020, and August 2022 were processed using solid phase extraction with a hydrophilic-lipophilic balance (HLB) cartridge and analyzed through ultra-high-performance liquid chromatography (UHPLC) with mass spectrometry. Risk quotients (RQ) were calculated as the ratio of measured environmental concentrations (MEC) to predicted no-effect concentrations (PNEC). Ciprofloxacin concentrations ranged from 5.62 to 9.34 µg/L, cefotaxime from 1.89 to 64.79 µg/L, and sulfamethoxazole from 29.11 to 248.77 µg/L, with higher concentrations observed during the wet season. MECs for ciprofloxacin, cefotaxime, and sulfamethoxazole exceeded their PNECs (RQ > 2), indicating a high risk of resistance development. Sulfamethoxazole posed the greatest risk due to its consistently elevated levels. In contrast, erythromycin concentrations remained below the PNEC, suggesting minimal resistance risk. These findings highlight the urgent need for wastewater treatment strategies to mitigate AMR risks in aquatic environments.