Characterization and mitigation of antimicrobial resistance genes in environmental water sources using metagenomic and culture-based approaches

Project Abstract

Environmental water systems act as dynamic reservoirs and conduits for antimicrobial resistance (AMR), facilitating the dissemination of resistance genes among diverse microbial communities and across ecological boundaries. This study employs an integrated metagenomic and culture-based framework to characterize the diversity, abundance, and functional potential of AMR determinants in surface water, groundwater, and wastewater effluents collected from urban, peri-urban, and agricultural interfaces. High-throughput shotgun sequencing was used to profile resistomes and mobilome signatures, enabling taxonomic attribution and the identification of plasmids, integrons, transposons, and other mobile genetic elements associated with resistance. Complementary culture-based isolation aimed to recover clinically relevant pathogens and commensals, establishing phenotypic resistance profiles and enabling genotypic confirmation of detected genes. By correlating metagenomic data with culture results and environmental metadata (pH, temperature, organic matter, nutrient levels, antimicrobial residues, rainfall, and land-use patterns), the study sought to elucidate drivers of AMR emergence, persistence, and horizontal gene transfer in aquatic environments. Bioinformatic pipelines integrated quality-filtered reads, assembly, annotation against curated AMR gene databases, and strain-level resolution using single-nucleotide variant analyses where possible. Quantitative assessments of gene abundance were normalized to 16S rRNA and total metagenomic read counts, with particular attention to clinically relevant ARGs including beta-lactamases (CTX-M, NDM, KPC), genes conferring resistance to fluoroquinolones, tetracyclines, macrolides, sulfonamides, and chloramphenicol, as well as determinants of reduced susceptibility via efflux pumps and permeability modification. Mobility potential was inferred by co-localization of ARGs with plasmid replicons and integron gene cassettes. The culture-based component focused on Enterobacterales, Pseudomonadales, and non-fermenting Gram-negative pathogens, employing selective media, matrix-assisted lasma desorption/ionization-time of flight (MALDI-TOF) identification, antimicrobial susceptibility testing, and whole-genome sequencing of representative isolates to validate resistance phenotypes and explore gene-context relationships. Statistical modeling and multivariate analyses characterized associations between environmental parameters and ARG abundance, revealing seasonal patterns and the impact of anthropogenic inputs such as hospital effluents and agricultural runoff. Network analyses uncovered potential co-selection dynamics, linking metal resistance determinants and biocide usage with ARG dissemination. The study also evaluated the effectiveness of conventional water treatment indicators in predicting residual AMR risk and assessed mitigation potential through scenario modelling of improved wastewater management and source control. Overall, findings demonstrated a broad, heterogeneous resistome across water types, with mobile ARGs circulating within and between microbial communities and detectable in downstream potable-relevant compartments. The integrated approach provided actionable insights into monitoring strategies, risk assessment, and targeted interventions to curb the environmental propagation of AMR through aquatic matrices.

Project Overview

What This Project Is About

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A simple look at how microbes in water can carry genes that make them resistant to antibiotics, and how we can detect and reduce these genes using two methods: looking at all the DNA in water samples (metagenomics) and growing microbes in the lab (culture-based).

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The Problem It Addresses

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Antibiotic resistance genes can spread through water from farms, sewage, and industry, making infections harder to treat. Traditional tests may miss some genes, so combining broad DNA screening with lab growth helps capture a fuller picture and identify practical ways to lower risks.

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Objectives of the Project

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1. Identify the range of resistance genes present in selected environmental water samples.
2. Compare results from metagenomic screening with culture-based findings.
3. Assess how common resistance genes are in different water sources (e.g., rivers, treated wastewater).
4. Suggest practical strategies to reduce the spread of these genes in the environment.

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What You Will Do Step by Step

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1. Collect water samples from chosen locations.

2. Extract total DNA and perform sequencing to detect resistance genes.

3. Plate samples on selective media to grow resistant bacteria and identify key strains.

4. Analyze sequencing data to map resistance genes to microbes and environments.

5. Compare metagenomic results with culture results to find overlaps and gaps.

6. Review water treatment or handling practices related to findings.

7. Propose feasible methods to reduce gene spread based on data.

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Expected Outcome

A clear picture of which resistance genes exist in environmental water and how often they appear, along with practical recommendations to limit their spread and improve water safety.