Understanding human health risks caused by antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG) in water environments: Current knowledge and questions to be answered

Abstract

Aquatic environments are identified as an ideal setting for acquisition and dissemination of antibiotic resistance, and human exposure to antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in aquatic environments may pose an additional health risk. Quantitative microbial risk assessment (QMRA) has been suggested as a suitable method to evaluate and quantify this health risk. However, information about the exposure to ARB and ARGs in aquatic environments is lacking for many scenarios and dose-response models regarding the ARB infections are not developed yet. This review summarizes the current knowledge regarding the ARB and ARGs in aquatic environments and highlights the challenging questions remaining to be answered to better forecast the health risks caused by ARB and ARGs in water environments. The questions include what are the missing information needed to quantify the human health risks caused by exposing to ARB and ARGs in aquatic environments? what are the suitable markers to evaluate the ARB/ARGs contamination in aquatic environments? how frequently do the ARG selection and propagation occur in aquatic environments? and are there any unknown hot spots? Studies on the above topics will contribute to better management of antibiotic resistance dissemination in water environments and its risks on human health.

Abbreviations
3GC	=	3rd generation cephalosporins
ARB	=	Antibiotic resistant bacteria
ARG	=	Antibiotic resistance gene
CFU	=	Colony forming unit
DBP	=	Disinfection by-products
eDNA	=	Extracellular DNA
EPS	=	Extracellular polymeric substances
HGT	=	Horizontal gene transfer
ISCR	=	Insertion sequence common region
MAR	=	Multiple antibiotic resistant
MIC	=	Minimum inhibitory concentration
MGE	=	Mobile genetic elements
MSW	=	Municipal solid waste
QMRA	=	Quantitative microbial risk assessment
VBNC	=	Viable but non-culturable
WWTP	=	Wastewater treatment plant

Graphical Abstract

Keywords:

• Antibiotic resistant bacteria
• antibiotic resistance genes
• quantitative microbial risk assessment

Disclosure statement

No potential conflict of interest

Additional information

Funding

This work was supported by the Japan Society for the Promotion of Science under Grants18K13855 and 16H01782, and by “The Sanitation Value Chain: Designing Sanitation Systems as Eco-Community Value System” Project from Research Institute for Humanity and Nature (RIHN, Project No. 14200107).