Comprehensive Study of Antibiotics and Antibiotic Resistance Genes in Wastewater and Impacted Mediterranean Water Environments

This comprehensive study investigated the presence and seasonal dynamics of antibiotics and antibiotic resistance genes (ARGs) in wastewater and impacted aquatic environments across two Mediterranean regions in Spain (Ebro River/Delta and Xúquer River/Albufera de València). Researchers analyzed samples for antibiotic residues and ARGs, with a particular focus on Escherichia coli, using a suspect screening approach and a novel prioritization method to identify areas most vulnerable to ARG spread. Results showed that while ARG levels remained relatively stable across seasons, a greater diversity of ARGs appeared in summer, likely driven by horizontal gene transfer in warmer waters (35–40 °C). In contrast, winter samples (5–10 °C) contained the highest concentrations of antibiotics, which may promote resistance development. These findings emphasize the critical role of environmental factors such as temperature and sunlight in shaping both antibiotic persistence and microbial resistance, underscoring the need for further research and targeted mitigation strategies in wastewater-impacted ecosystems.