Key determinants of antimicrobial resistance: exploring the influence of antibiotic pollution on the emergence of multidrug-resistant microbes

Antimicrobial resistance (AMR) is increasingly driven by environmental contamination with antibiotics. Residues from agriculture, healthcare, and inadequate wastewater treatment enter aquatic systems, where even low (subinhibitory) concentrations promote the selection of antibiotic-resistant genes (ARGs) and multidrug-resistant (MDR) microbes, largely through horizontal gene transfer (HGT). Environmental co-selectors such as heavy metals and pesticides further accelerate resistance development. These resistant organisms and genes can re-enter the human microbiome via food, water, and direct contact, leading to difficult-to-treat infections. The chapter highlights the need for improved monitoring and control of antibiotic pollution, including advanced detection methods, innovative wastewater treatment strategies (e.g., bacteriophages, cyanobacteria), and nanotechnology-based approaches. It calls for coordinated, systemic changes in waste management and antibiotic use to curb environmental pollution and mitigate the global spread of MDR.