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

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.Abbreviations3GC3rd generation cephalosporinsARBAntibiotic resistant bacteriaARGAntibiotic resistance geneCFUColony forming unitDBPDisinfection by-productseDNAExtracellular DNAEPSExtracellular polymeric substancesHGTHorizontal gene transferISCRInsertion sequence common regionMARMultiple antibiotic resistantMICMinimum inhibitory concentrationMGEMobile genetic elementsMSWMunicipal solid wasteQMRAQuantitative microbial risk assessmentVBNCViable but non-culturableWWTPWastewater treatment plant