Antibiotic resistance genes as an emerging environmental contaminant

Emerging contaminants, including pharmaceutical and personal care products, are receiving considerable attention owing to their potential to negatively impact the environment and to pose risks to human health. The widespread use of antibiotics and their fate and transport in the environment pose further risks with respect to public health and the development of antibiotic resistant organisms (AROs). While the occurrence of AROs is important, there is increasing interest in antibiotic resistance genes (ARGs). An urgent need exists to improve our understanding of the mechanisms associated with the spread and development of ARGs in both clinical and veterinary settings, the human body (gastrointestinal tract and microbiome) as well as in engineered (wastewater treatment plants) and natural (soil, sediments and water) environments. This review focuses on ARGs as an emerging environmental contaminant. The factors and mechanisms involved in ARG dissemination in a variety of environments are explored in detail. The unique challenges of ARGs with respect to policy-making and environmental monitoring are identified, and recommendations regarding how these challenges might be addressed are provided.