Mapping antimicrobial resistance landscape at a city scale sewage network

Area of Science:

• Environmental microbiology
• Public health
• Genomics

Background:

• Antimicrobial resistance (AMR) is a growing global health threat.
• Antimicrobial resistance genes (ARGs) are increasingly detected in various ecosystems.
• Identifying hotspots of ARG dissemination is crucial for effective control strategies.

Purpose of the Study:

• To investigate the city-scale distribution and abundance of ARGs in wastewater.
• To identify specific ARG types and their prevalence in different urban areas.
• To assess the effectiveness of wastewater treatment plants (WWTPs) in reducing ARG loads.

Main Methods:

• Integrated metagenomic and culture-based techniques coupled with whole-genome sequencing (WGS).
• Analysis of seven sampling sites across the sewage system of Sabadell, Spain.
• Quantification and characterization of ARG variants and antibiotic-resistant bacterial isolates.

Main Results:

• Identified 262 ARG variants, with macrolides-lincosamides-class B streptogramins (MLS_B) and beta-lactams being the most prevalent.
• The hospital sector showed the highest ARG abundance, while WWTP effluent had the lowest.
• WWTPs achieved a significant reduction (93.3%) in ARG presence.
• Plasmids were confirmed as major drivers of ARG dissemination in waterborne bacteria.

Conclusions:

• City-scale wastewater surveillance effectively identifies ARG hotspots.
• Hospital wastewater is a significant contributor to ARG pollution.
• WWTPs play a critical role in reducing the environmental burden of ARGs.
• Understanding ARG dissemination via plasmids is key to developing targeted interventions.