Characterization of antimicrobial resistance mechanisms in gut microbiota of clinically healthy individuals using metagenomic and culture-based approaches

Project Abstract

Characterization of antimicrobial resistance mechanisms in gut microbiota of clinically healthy individuals using metagenomic and culture-based approaches explores the landscape of resistance determinants harbored by the gut microbiota in asymptomatic adults and how these determinants are expressed and potentially mobilized. By integrating culture-dependent isolation with culture-independent sequencing, this study aims to delineate both phenotypic resistance profiles and the resistome, providing a comprehensive view of how antimicrobial resistance genes (ARGs) are distributed across dominant commensals and less abundant taxa. High-throughput metagenomic sequencing coupled with targeted long-read sequencing will be employed to capture ARGs, their genomic contexts, and associated mobile genetic elements such as plasmids, transposons, and integrons. Parallel culture-based methods will isolate representative gut bacteria to determine minimum inhibitory concentrations (MICs) for a panel of clinically relevant antibiotics, enabling correlation between detected ARGs and actual resistance phenotypes. Functional metagenomics will be used to validate novel or uncertain resistance determinants by expressing environmental DNA in surrogate hosts and screening for antibiotic resistance phenotypes, thereby expanding the catalog of functional ARGs. The study will also investigate the co-occurrence patterns of ARGs with virulence factors and transport systems to assess potential fitness costs and ecological drivers of ARG maintenance within the healthy gut milieu. A cross-sectional cohort of diverse adult participants will be recruited, with careful stratification by age, sex, diet, recent antibiotic exposure, traveling history, and health status to minimize confounding factors. Bioinformatic pipelines will annotate resistance genes against curated databases (e.g., CARD, ResFinder, ARG-ANNOT) and quantify their relative abundance using standardized metrics. Statistical analyses will examine associations between microbiome composition, ARG burden, and metadata, while network analyses will reveal potential hubs of resistance dissemination. Ethical considerations include informed consent, data privacy, and responsible reporting of incidental findings. Anticipated outcomes include a detailed resistome map of the healthy gut, identification of core and variable ARGs, and insights into the contribution of commensal communities to the reservoir of antimicrobial resistance. The study also aims to identify oral and dietary or environmental factors that correlate with higher ARG carriage, contributing to preventive strategies in community health and informing antibiotic stewardship. By integrating multi-omics data with phenotypic and functional validation, this research seeks to elucidate how antimicrobial resistance persists in the absence of disease, the role of horizontal gene transfer in healthy individuals, and the potential risk this reservoir poses for future clinical settings. The findings are expected to advance understanding of baseline resistance landscapes, improve interpretation of gut microbiome data in clinical contexts, and guide future longitudinal studies on ARG dynamics in relation to antibiotic use and lifestyle factors.

Project Overview

What This Project Is About

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A plain-language overview of the topic and what the project investigates.

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The Problem It Addresses

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What problem or gap this project tackles and why it matters to the field or society.

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Objectives of the Project

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1. Identify the types of antimicrobial resistance found in gut bacteria from healthy individuals.
2. Compare resistance patterns detected by culture methods with those found by metagenomic analysis.
3. Explain how gut microbes contribute to the overall reservoir of resistance genes.
4. Assess how lifestyle factors might influence resistance presence in the gut.

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What You Will Do Step by Step

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Step-by-step plan in simple terms:

1. Collect stool samples from a small group of healthy volunteers after getting consent and ethical approval.
2. Grow bacteria from samples in the lab to test their response to common antibiotics.
3. Extract DNA from samples to look for resistance genes using sequencing methods.
4. Compare results from lab cultures with the DNA-based findings to see if they match.
5. Summarize which resistance genes are present and how widespread they are.

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Expected Outcome

Expect to identify a set of common resistance genes in the gut of healthy people and understand how well culture tests reflect the genetic data. The project should highlight the potential of gut microbes to share resistance traits and inform future monitoring or public health efforts.