Characterization and Comparative Genomics of Antimicrobial Resistance Mechanisms in Clinical Isolates of Escherichia coli from Diverse Geographic Regions

Project Abstract

This study investigates the characterization and comparative genomics of antimicrobial resistance (AMR) mechanisms in clinical isolates of Escherichia coli collected from diverse geographic regions, aiming to elucidate the genetic basis, distribution, and evolution of resistance determinants that influence treatment outcomes. We integrated phenotypic antimicrobial susceptibility testing with whole-genome sequencing (WGS) and robust bioinformatic analyses to map resistance genes, plasmid content, and chromosomal mutations associated with resistance to beta-lactams, fluoroquinolones, aminoglycosides, tetracyclines, and sulfonamides. A collection of 400 E. coli isolates was gathered from tertiary hospitals across five continents, ensuring representation of regional clonal lineages and varying clinical contexts such as bloodstream infections, urinary tract infections, and intra-abdominal infections. Phenotypic screening identified high prevalence of multidrug resistance (MDR) and extended-spectrum beta-lactamase (ESBL) producers, with notable regional variation in resistance profiles. WGS data were subjected to multilocus sequence typing (MLST), core-genome phylogenomics, resistome and mobilome profiling (CARD, ResFinder, PlasmidFinder), and comparative genomics to detect lineage-specific AMR signatures, plasmid backbones, integron structures, and transposon-associated resistance islands. Our analyses reveal that AMR in E. coli is driven by a combination of disseminated ESBL/plasmid-mediated beta-lactamases (e.g., blaCTX-M variants) and chromosomal mutations in quinolone resistance-determining regions (QRDRs), with regional biases linked to predominant sequence types such as ST131 and its subclones. The study uncovers novel plasmid backbones carrying novel combinations of ESBLs and carbapenemase-related genes in certain regions, highlighting the dynamic exchange of resistance determinants via horizontal gene transfer. Comparative genomics demonstrates convergent evolution of AMR mechanisms across diverse lineages, underscoring the role of selective antibiotic pressure in shaping resistomes within clinical settings. We also assess the fitness costs and compensatory mutations associated with resistance, providing insight into the persistence and spread of MDR clones in hospital ecosystems. Phylogenetic analyses reveal clonal expansion events correlated with regional antibiotic stewardship practices, infection control policies, and patient populations. Additionally, we identify mobile genetic elements, such as integrons and transposons, as key vectors propagating resistance islands across species barriers, signaling potential reservoirs of AMR genes beyond E. coli. The study integrates epidemiological metadata with genomic data to map transmission networks and identify hotspots of resistance emergence. Our findings have direct implications for surveillance, diagnostic stewardship, and targeted intervention strategies to mitigate the spread of MDR E. coli. The research contributes a high-resolution, population-level view of AMR dissemination and provides a framework for real-time genomic surveillance that can be adapted to other Enterobacterales, informing global and regional public health responses to antimicrobial resistance.

Project Overview

What This Project Is About

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A plain-language overview of how harmless samples of E. coli from different places are studied to understand how they become resistant to common antibiotics and what the genetic clues tell us about this resistance. Researchers compare the DNA of resistant and non-resistant strains to see which genes are linked to resistance and how these genes spread between bacteria and across regions. The goal is to connect clinical observations with the underlying genetic mechanisms in a way that's accessible to undergraduates.

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The Problem It Addresses

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Antibiotic resistance is making many infections harder to treat. Not all resistance genes act the same in different regions or patient groups, and we need a clearer picture of which genes are most important, how they are transferred, and how regional differences affect their spread. This study helps identify targets for surveillance, treatment decisions, and public health strategies.

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Objectives of the Project

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1. Identify key antimicrobial resistance genes in Escherichia coli from diverse geographic regions.
2. Compare the genetic contexts of resistance genes to understand how they move between bacteria.
3. Assess the relationship between resistance gene presence and antibiotic susceptibility patterns.
4. Describe differences in resistance profiles across regions and clinical settings.
5. Build a simple framework for monitoring resistance in local laboratories.

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What You Will Do Step by Step

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1. Collect or access bacterial isolates from multiple geographic regions.
2. Perform basic lab language: confirm species and test antibiotic susceptibility.
3. Extract DNA and sequence key resistance genes and whole genomes if available.
4. Analyze sequence data to identify resistance genes and their genetic surroundings.
5. Compare data across isolates to identify patterns and regional differences.
6. Summarize findings in a student-friendly report with simple visuals.

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Expected Outcome

A clear set of common and region-specific resistance genes in E. coli, with explanations of how these genes spread and what that means for treatment and surveillance. The project should yield a concise report and some practical recommendations for local monitoring efforts.