Bacterial resistance is a naturally occurring process. However, bacterial antibiotic resistance has emerged as a major public health problem in recent years. The accumulation of antibiotics in the environment, including in wastewaters and drinking water, has contributed to the development of antibiotic resistant bacteria and the dissemination of antibiotic resistance genes (ARGs). Such can be justified by the growing consumption of antibiotics and their inadequate elimination. The conventional water treatments are ineffective in promoting the complete elimination of antibiotics and bacteria, mainly in removing ARGs. Therefore, ARGs can be horizontally transferred to other microorganisms within the aquatic environment, thus promoting the dissemination of antibiotic resistance. In this review, we discuss the efficiency of conventional water treatment processes in removing agents that can spread/stimulate the development of antibiotic resistance and the promising strategies for water remediation, mainly those based on nanotechnology and microalgae. Despite the potential of some of these approaches, the elimination of ARGs remains a challenge that requires further research. Moreover, the development of new processes must avoid the release of new contaminants for the environment, such as the chemicals resulting from nanomaterials synthesis, and consider the utilization of green and eco-friendly alternatives such as biogenic nanomaterials and microalgae-based technologies.

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Antibiotic Resistance in the Drinking Water: Old and New Strategies to Remove Antibiotics, Resistant Bacteria, and Resistance Genes

Cyanobacterial harmful algal blooms (cyanoHABs) are an ecological concern because of large ecosystem-disrupting blooms and a global public health concern because of the cyanotoxins produced by certain bloom-forming species. Another threat to global public health is the dissemination of antibiotic resistance (AR) in freshwater environmental reservoirs from anthropogenic sources, such as wastewater discharge and urban and agricultural runoff. In this study, cyanobacteria are now hypothesized to play a role in the environmental resistome. A non-systematic literature review of studies using molecular techniques (such as PCR and metagenomic sequencing) was conducted to explore indirect and direct ways cyanobacteria might contribute to environmental AR. Results show cyanobacteria can host antibiotic resistance genes (ARGs) and might promote the spread of ARGs in bacteria due to the significant contribution of mobile genetic elements (MGEs) located in genera such as Microcystis. However, cyanobacteria may promote or inhibit the spread of ARGs in environmental freshwater bacteria due to other factors as well. The purpose of this review is to 1) consider the role of cyanobacteria as AR hosts, since cyanoHABs are historically considered to be a separate problem from AR, and 2) to identify the knowledge gap in understanding cyanobacteria as ARG reservoirs. Cyanobacterial blooms, as well as other biotic (e.g. interactions with protists or cyanophages) and abiotic factors, should be studied further using advanced methods such as shotgun metagenomic and long read sequencing to clarify the extent of their functional ARGs/MGEs and influences on environmental AR. 

Cyanobacterial blooms: A player in the freshwater environmental resistome with public health relevance?

The significance of metallic nanoparticles in the emerging, development and spread of antibiotic resistance.

Prevalence of antimicrobial resistance in a full-scale drinking water treatment plant.

Antibiotic resistance is widely acknowledged as one of the most challenging global crises at hand. Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are ubiquitously detected as emerging biological contaminants. Several human lives are currently perished due to untreated infections for the emergence of antibiotic resistance. Semi-metabolized antibiotic residue from human faeces and effluents of the pharmaceutical industry are released into municipal wastewater. This in turn triggers the selection of ARGs and ARB, which eventually seek a way into natural environmental matrices. To this end, the unique physicochemical properties of nanomaterials, such as enormous surface area and higher surface reactivity, benefit them to get nominated as an emerging tool to combat antibiotic resistance. As such, tremendous research and development efforts are currently underway to achieve meaningful progress in the development and deployment of innovative nanotechnology-based treatment strategies with high removal efficacy for ARGs and ARB. Nano-enabled water/wastewater treatment system offer perquisites of being energy efficient, effectual, durable, and cost-effective. Although nanotechnological approaches are gaining momentum, the major challenge in terms of commercialization is that long term efficacy of nano-based treatment under realistic conditions remains relatively unknown. This review is intended to accentuate the potentiality of nanotechnology and nanomaterials in ARGs and ARB removal. Additionally, several noble detection technologies that are currently in use as well as those that are in the process of deployment beyond the laboratory scale are enumerated. 

Yunchao Tang

Papers

The effect of carbon-based copper nanocomposites on Microcystis aeruginosa and the movability of antibiotic resistance genes in urban water.