Antimicrobial resistance in urban river ecosystems.

Antimicrobial resistance (AMR) with the ability to thwart clinical therapies and escalate mortality rates is emerging as one of the most pressing global health and environmental concerns. Urban rivers as an important subsystem of the environment offer galore of ecological services which benefit the city dwellers. However, with increased urbanization, industrialization, and heavy discharge of anthropogenic waste harboring antibiotics, heavy metals, pesticides, antibiotic resistance genes (ARGs), antibiotic resistant bacteria (ARB), urban rivers are becoming major reservoirs of ARGs and a hotspot for accelerated selection of ARB. These ARGs in urban rivers have the potential of being transferred to clinically important pathogens. In addition, urban rivers also act as important vectors for AMR spread. This is mainly due to the direct exposure of humans and animals to the heavily contaminated river water and high mobility of organisms (aquatic animals, pathogenic, non-pathogenic bacteria) as well as the genetic elements including ARGs and mobile genetic elements (MGEs) in the river. However, in spite of recent advocacy for comprehensive research programs aimed to investigate the occurrence, extent and major drivers of AMR in urban rivers globally, such studies are missing largely. This review encompasses the issues of AMR, major drivers and their vital roles in the evolution and spread of ARB with an emphasis on sources and hotspots of diverse ARGs in urban rivers contributing to co-occurrence of ARGs and MGEs. Further, the causal factors leading to adverse effects of antibiotic-load to river organisms with an elaboration on the current measures to eradicate the ARB, ARGs, and remove antibiotics from the urban river ecosystems are also discussed. A perspective review of current and emerging strategies with potentials of combating AMR in urban river ecosystems including advanced water treatment methodologies and floating islands or constructed wetlands.

Microplastic-associated pathogens and antimicrobial resistance in environment.

The ubiquitous use of microplastics and their release into the environment especially the water bodies by anthropogenic/industrial activities are the major resources for microplastic contamination. The widespread and often injudicious use of antimicrobial drugs or antibiotics in various sectors including human health and hygiene, agriculture, animal husbandry and food industries are leading to the release of antibiotics into the wastewater/sewage and other water bodies, particularly in urban setups and thus leads to the antimicrobial resistance (AMR) in the microbes. Microplastics are emerging as the hubs as well as effective carriers of these microbial pathogens beside their AMR-genes (ARGs) in marine, freshwater, sewage/wastewater, and urban river ecosystems. These drug resistant bacteria interact with microplastics forming synthetic plastispheres, the ideal niche for biofilm formations which in turn facilitates the transfer of ARGs via horizontal gene transfer and further escalates the occurrence and levels of AMR. Microplastic-associated AMR is an emerging threat for human health and healthcare besides being a challenge for the research community for effective management/address of this menace. In this review, we encompass the increasing prevalence of microplastics in environment, emphasizing mainly on water environments, how they act as centers and vectors of microbial pathogens with their associated bacterial assemblage compositions and ultimately lead to AMR. It further discusses the mechanistic insights on how microplastics act as hosts of biofilms (creating the plastisphere). We have also presented the modern toolbox used for microplastic-biofilm analyses. A review on potential strategies for addressing microplastic-associated AMR is given with recent success stories, challenges and future prospects.

Combating Drug-Resistant Bacteria Using Photothermally Active Nanomaterials: A Perspective Review.

Injudicious use of antibiotics has been the main driver of severe bacterial non-susceptibility to commonly available antibiotics (known as drug resistance or antimicrobial resistance), a global threat to human health and healthcare. There is an increase in the incidence and levels of resistance to antibacterial drugs not only in nosocomial settings but also in community ones. The drying pipeline of new and effective antibiotics has further worsened the situation and is leading to a potentially "post-antibiotic era." This requires novel and effective therapies and therapeutic agents for combating drug-resistant pathogenic microbes. Nanomaterials are emerging as potent antimicrobial agents with both bactericidal and potentiating effects reported against drug-resistant microbes. Among them, the photothermally active nanomaterials (PANs) are gaining attention for their broad-spectrum antibacterial potencies driven mainly by the photothermal effect, which is characterized by the conversion of absorbed photon energy into heat energy by the PANs. The current review capitalizes on the importance of using PANs as an effective approach for overcoming bacterial resistance to drugs. Various PANs leveraging broad-spectrum therapeutic antibacterial (both bactericidal and synergistic) potentials against drug-resistant pathogens have been discussed. The review also provides deeper mechanistic insights into the mechanisms of the action of PANs against a variety of drug-resistant pathogens with a critical evaluation of efflux pumps, cell membrane permeability, biofilm, and quorum sensing inhibition. We also discuss the use of PANs as drug carriers. This review also discusses possible cytotoxicities related to the therapeutic use of PANs and effective strategies to overcome this. Recent developments, success stories, challenges, and prospects are also presented.