Sources, dissemination, and risk assessment of antibiotic resistance in surface waters: A review

The development and spread of antibiotic resistance (AR) have become major concerns because they pose pressing public health problems worldwide, and aquatic ecosystems are recognized reservoirs for antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB). We reviewed the sources, distribution, and factors influencing ARGs and ARB in surface waters, and the methods used to measure and assess the risks posed to human and ecological health. The prevalence of ARGs and ARB is largely attributed to environmental contamination from fecal matter. Therefore, the distribution of AR on both regional and seasonal scales is significantly impacted by agriculture, which is related to economic development. In risk assessments, the risk of ARGs is mainly evaluated based on their mobility, pathogen carriage, and regional distribution, while the risk assessment for ARB is primarily focused on the quantities and diversities of pathogen-associated resistant bacteria. Based on this information, we suggest seven priority research questions regarding antibiotic resistance management in water environments: control of AR dissemination, advanced monitoring technologies, integrative impacts evaluation of antibiotics on resistance mechanisms and microbial communities, quantitative microbial risk assessment for ARB and ARGs, implications of horizontal gene transfer in non-pathogenic bacteria, synergistic risks of multiple resistance elements, and identification of high-risk ARGs and ARB in aquatic ecosystems. We also advocate for the implementation of national actions that focus on source management and environmental monitoring.