Antibiotic-Resistant Genes and Bacteria as Evolving Contaminants of Emerging Concerns (e-CEC): Is It Time to Include Evolution in Risk Assessment?

Abstract

The pressing issue of the abundance of antibiotic resistance genes and resistant bacteria in the environment (ARGs and ARB, respectively) requires procedures for assessing the risk to health. The chemo-centric environmental risk assessment models identify hazard(s) in a dose–response manner, obtaining exposure, toxicity, risk, impact and policy. However, this risk assessment approach based on ARGs/ARB evaluation from a quantitative viewpoint shows high unpredictability because ARGs/ARB cannot be considered as standard hazardous molecules: ARB duplicate and ARGs evolve within a biological host. ARGs/ARB are currently listed as Contaminants of Emerging Concern (CEC). In light of such characteristics, we propose to define ARGs/ARB within a new category of evolving CEC (or e-CEC). ARGs/ARB, like any other evolving determinants (e.g., viruses, bacteria, genes), escape environmental controls. When they do so, just one molecule left remaining at a control point can form the origin of a new dangerous and selection-responsive population. As a consequence, perhaps it is time to acknowledge this trait and to include evolutionary concepts within modern risk assessment of e-CEC. In this perspective we analyze the evolutionary responses most likely to influence risk assessment, and we speculate on the means by which current methods could measure evolution. Further work is required to implement and exploit such experimental procedures in future risk assessment protocols.

Antimicrobial Resistance Monitoring of Water Environments: A Framework for Standardized Methods and Quality Control

“…The environment is now recognized not as only a key avenue for AMR transmission, e.g., from fecal sources to potential points of exposure, but also as a source of acquisition of new ARGs by pathogens. − A major challenge is that ARGs can be shared among bacteria via mobile genetic elements (MGEs), and therefore it is necessary to consider their movement along with ARB and ARGs in the environment. The current understanding is that most ARGs found in pathogens were originally recruited from the vast and diverse genetic reservoir embodied by environmental bacteria .…”

Targeting current and future threats: recent methodological trends in environmental antimicrobial resistance research and their relationships to risk assessment

“…These challenges have so far limited the number of studies examining MGEs in an environmental risk framework. 136 There is some evidence that the risk associated with different MGEs varies. Prophages seemingly are less likely to carry ARGs than other elements, 137 and plasmids can be grouped based on their promiscuity, 138 but more work is needed to make these measures useful.…”

Effect of Wastewater on the Composition of Bacterial Microbiota of Phragmites australis Used in Constructed Wetlands for Phytodepuration

“…This goal is achieved using constructed wetlands (CW), which are engineered systems designed to mimic the natural processes occurring in natural wetlands, although in a more controlled environment, to remove organic compounds, suspended solids, microbes, and heavy metals [ 2 ]. Moreover, as recently reviewed, CW can also limit the diffusion of antibiotics, antimicrobial resistance genes (ARGs), and antibiotic resistant bacteria (ARB) [ 1 ]; these are listed among the so-called “contaminants of emerging concern” (CEC), and their presence in wastewater may represent a serious danger as they can escape typical controls, spread in the environment, and even evolve [ 3 ]. Indeed, the new term “evolving CEC” (e-CEC) has been proposed for ARGs and ARB [ 3 ].…”

“…Moreover, as recently reviewed, CW can also limit the diffusion of antibiotics, antimicrobial resistance genes (ARGs), and antibiotic resistant bacteria (ARB) [ 1 ]; these are listed among the so-called “contaminants of emerging concern” (CEC), and their presence in wastewater may represent a serious danger as they can escape typical controls, spread in the environment, and even evolve [ 3 ]. Indeed, the new term “evolving CEC” (e-CEC) has been proposed for ARGs and ARB [ 3 ]. CW are recognized as a reliable technology for wastewater treatment, as well as being sustainable and cost-effective [ 4 ]; in fact, their use for the treatment of different types of wastewater has been reported, such as those from municipal, farm, and industrial sources [ 5 ].…”