We applied metagenomic sequencing to comprehensively evaluate drivers of antibiotic resistance spread along a Bolivian river, La Paz, which has a high load of untreated wastewater and documented presence of multidrug-resistant enteric pathogens.
Wastewater containing emergent pollutants is considered to play a key role in the emergence, mobilization, and dissemination of antibiotic resistance. Nevertheless, little is known about its dynamics beyond wastewater treatment plants. Hence, we studied how untreated wastewater influences the composition, diversity and antimicrobial resistance of riverine microbial communities. We applied metagenomic sequencing to comprehensively evaluate drivers of antibiotic resistance spread along a Bolivian river, La Paz, which has a high load of untreated wastewater and documented presence of multidrug-resistant enteric pathogens. Sewage pollution significantly reduced the taxonomic diversity of aquatic bacterial communities, particularly in sediments, and shifted their compositions toward an elevated abundances of gut-associated bacteria (i.e., Firmicutes and Fusobacteriota). In contrast, sewage input markedly increased both the richness and abundance of antibiotic resistance genes (ARGs). This rise in ARG abundance showed only a weak association with fecal pollution, indicating that additional factors may have contributed to ARG proliferation. Indeed, our findings suggest that antibiotic residues, especially ß-lactams in the water column and macrolides in sediments, could promote in situ selection, enhancing ARG abundance. Aeromonas and Acinetobacter were identified as potential ARG reservoirs within the river ecosystem. The strong association between ARGs and mobile genetic elements highlights the potential for their transfer through plasmid conjugation, underscoring enhanced mobilization of ARGs in highly polluted aquatic environments
Wastewater containing emergent pollutants is considered to play a key role in the emergence, mobilization, and dissemination of antibiotic resistance. Nevertheless, little is known about its dynamics beyond wastewater treatment plants. Hence, we studied how untreated wastewater influences the composition, diversity and antimicrobial resistance of riverine microbial communities. We applied metagenomic sequencing to comprehensively evaluate drivers of antibiotic resistance spread along a Bolivian river, La Paz, which has a high load of untreated wastewater and documented presence of multidrug-resistant enteric pathogens. Sewage pollution significantly reduced the taxonomic diversity of aquatic bacterial communities, particularly in sediments, and shifted their compositions toward an elevated abundances of gut-associated bacteria (i.e., Firmicutes and Fusobacteriota). In contrast, sewage input markedly increased both the richness and abundance of antibiotic resistance genes (ARGs). This rise in ARG abundance showed only a weak association with fecal pollution, indicating that additional factors may have contributed to ARG proliferation. Indeed, our findings suggest that antibiotic residues, especially ß-lactams in the water column and macrolides in sediments, could promote in situ selection, enhancing ARG abundance. Aeromonas and Acinetobacter were identified as potential ARG reservoirs within the river ecosystem. The strong association between ARGs and mobile genetic elements highlights the potential for their transfer through plasmid conjugation, underscoring enhanced mobilization of ARGs in highly polluted aquatic environments
Chalmers University of Technology