Comprehensive analysis and risk assessment of antibiotic contaminants and the antibiotic resistance of Escherichia coli from crested ibis

The environmental quality of habitat is a critical determinant of animal survival. In this study, we conducted a comprehensive analysis of ten antibiotic residues in habitats of the crested ibis (Nipponia nippon). Results indicated that tetracyclines (TCs) were the most predominant species, constituting over 89 % of the total antibiotics detected. A comprehensive risk assessment revealed that oxytetracycline (OTC) and sulfamethoxazole (SMZ) posed medium and high ecological risk, respectively, based on risk quotients (RQ) analysis. Higher antibiotic concentrations and ecological risks were observed in the Hanzhong region compared to other areas. Furthermore, antimicrobial susceptibility testing of Escherichia coli isolates from crested ibis showed complete resistance to TC and chlortetracycline (CTC), as well as high resistance rates to ciprofloxacin (CIP), norfloxacin (NOR) and enrofloxacin (ENR). The antibiotic resistance genes tetA, gryB, bla_TEM and bla_SHV were highly prevalent among the isolates. Notably, E. coli isolates from Hanzhong region exhibited higher resistance rate and a greater variety of antibiotic resistance genes. These findings could enhance our understanding of antibiotic contamination and the associated spread of antimicrobial resistance of E. coli within crested ibis habitats, providing a scientific basis for improved antibiotic risk management in these ecosystems.