Comparison of domestic and mixed wastewater reveals limited impact of hospital effluent discharge on antibiotic resistance
Antimicrobial resistance (AMR) is a global health concern, with projections estimating it to cause up to 39 million deaths by 2050. Environmental compartments, particularly wastewater, are recognised as important reservoirs for antibiotic-resistant bacteria and antibiotic resistance genes (ARGs). Hospital wastewater (HWW) has been shown to contain higher concentrations of ARGs, especially clinically relevant ARGs, compared to domestic wastewater (DWW), raising concerns about its potential role in the dissemination of AMR. Here, we conducted a multi-year monitoring study comparing HWW, DWW, and mixed wastewater (MWW; i.e., DWW receiving HWW), using both culture-based techniques and molecular analyses. Our results showed that HWW harboured significantly higher levels of resistant and multidrug-resistant bacteria than both DWW and MWW. The relative abundance of most ARGs was also higher in HWW. Microbial community analysis further revealed that HWW was dominated by human commensal bacteria, while DWW and MWW were largely composed of environmental species. Overall, only a few differences were observed between DWW and MWW, likely due to substantial dilution of the HWW input and a shift in microbial communities. A notable exception was the high relative abundance of carbapenemase-encoding genes blaIMP, blaKPC, blaNDM and blaVIM in MWW, which was associated with HWW exposure. This study provided valuable insight into antibiotic resistance dynamics in urban wastewater systems and contribute important evidence to guide future environmental and public health regulations.
Antimicrobial resistance (AMR) is a global health concern, with projections estimating it to cause up to 39 million deaths by 2050. Environmental compartments, particularly wastewater, are recognised as important reservoirs for antibiotic-resistant bacteria and antibiotic resistance genes (ARGs). Hospital wastewater (HWW) has been shown to contain higher concentrations of ARGs, especially clinically relevant ARGs, compared to domestic wastewater (DWW), raising concerns about its potential role in the dissemination of AMR. Here, we conducted a multi-year monitoring study comparing HWW, DWW, and mixed wastewater (MWW; i.e., DWW receiving HWW), using both culture-based techniques and molecular analyses. Our results showed that HWW harboured significantly higher levels of resistant and multidrug-resistant bacteria than both DWW and MWW. The relative abundance of most ARGs was also higher in HWW. Microbial community analysis further revealed that HWW was dominated by human commensal bacteria, while DWW and MWW were largely composed of environmental species. Overall, only a few differences were observed between DWW and MWW, likely due to substantial dilution of the HWW input and a shift in microbial communities. A notable exception was the high relative abundance of carbapenemase-encoding genes blaIMP, blaKPC, blaNDM and blaVIM in MWW, which was associated with HWW exposure. This study provided valuable insight into antibiotic resistance dynamics in urban wastewater systems and contribute important evidence to guide future environmental and public health regulations.
Therapeutic Innovations and Resistances