The Fate of Antibiotic-Resistant Bacteria in the Environment

The discovery of antibiotics in the twentieth century largely improved health conditions. However, the increasing and disproportionate use of these drugs has led to the emergence of antibiotic-resistant bacteria. Currently, these antibiotic-resistant bacteria are spreading within the human community. Our environment is polluted by these emerging contaminants, mostly through the effluents of wastewater treatment plants and soil amendments with residual organic waste. Farming, intensive pasturing, and aquacultures are also sources of antibiotic-resistant bacteria in the environment. Once released into the environment, antibiotic-resistant bacteria spread mostly in aquatic ecosystems where they can persist in culturable or non-culturable states. Together with antibiotic-resistant bacteria, antimicrobials (i.e. antibiotics, metals and biocides) are released most often from the same sources and can exert selective pressure on bacterial communities. To what extent are environments contaminated with antibiotic-resistant bacteria a new risk for human populations? Humans in low and middle income countries are more frequently exposed than humans in high income countries, benefiting from the efficient collection and treatment of wastewater. Indeed, various management measures can be implemented to reduce the likelihood of human exposure to environmental antibiotic resistance and the subsequent risk to human health; such measures include efficient wastewater treatments, the implementation of local policies and knowledge exchange. Moreover, as the spread of antibiotic resistance is both a public and an environmental health concern, this issue can only be understood through a multidisciplinary approach that involves all stakeholders.