Antimicrobial resistance and the human gut microbiome-a food safety perspective

Every time we eat, our gut microbiome is exposed not just to nutrients but also to bacteria, resistance genes, and antimicrobial residues that arrive with food. This review asks a pressing question: does what we eat meaningfully change which antibiotic-resistance genes (ARGs) live in our gut, and under what conditions can those genes spread to our resident bacteria? The authors synthesize current evidence on how the gut environment — its microbial density, composition, and ecological barriers — either blocks or facilitates horizontal gene transfer from food-derived microbes to permanent gut residents. A key insight is that most bacteria we swallow are transient and face strong 'colonisation resistance' from the established microbiome, but this protection is not absolute and poorly characterised in living humans. Factors such as antimicrobial residues in food, mobile genetic elements, and host physiology can all tip the balance, yet their relative importance remains unresolved. Methodological inconsistency across studies — different animal models, sequencing approaches, and dietary exposures — makes it very hard to compare findings or draw regulatory conclusions. The review concludes that closing these knowledge gaps is essential for credible AMR risk assessment in food safety policy.

• Resistant bacteria and ARGs are frequently detected in food and food production environments, but their quantitative contribution to the human gut resistome has not been established — a central gap the review documents across the available literature.
• Most ingested microorganisms are transient and subject to ecological barriers (colonisation resistance); however, the specific host, microbial, and dietary conditions under which horizontal gene transfer occurs in vivo remain poorly characterised.
• Multiple interacting factors — including microbial community composition and density, mobile genetic elements, antimicrobial residues, fitness costs of resistance, and host physiology — can modulate ARG persistence and mobility in the gut, but no consensus exists on their relative contributions.
• Methodological variability across studies (animal models, sequencing platforms, experimental diets) severely limits cross-study comparability, and in vivo human data are particularly scarce, restricting the evidence base for regulatory risk assessment.

This is a narrative critical review, not a primary experimental study. The authors systematically surveyed published literature on AMR dynamics in the gastrointestinal tract following dietary exposure, drawing on in vitro models, animal studies, and the limited available human data. No primary cohort, sample size, or intervention protocol applies; the review synthesises mechanistic, ecological, and epidemiological evidence to map knowledge gaps. The scope spans the full farm-to-gut chain: food production environments, food matrices, ingestion dynamics, and intragastrointestinal ARG transfer mechanisms.

Because this is a review, it inherits the limitations of the underlying literature: heavy reliance on animal and in vitro models that may not replicate human gut conditions, and a near-absence of controlled in vivo human studies tracking ARG acquisition from specific dietary exposures. Methodological heterogeneity among primary studies prevents meta-analytic synthesis or quantitative risk estimates. The review cannot establish causality or determine threshold dietary exposures that meaningfully shift the gut resistome. The next critical experiments would be longitudinal human dietary intervention trials combining metagenomics, metatranscriptomics, and culturomics to track ARG dynamics in real time following defined food exposures.

This review extends [§100], which frames the human microbiome through an ecological and causal lens, by applying that same ecological reasoning specifically to ARG acquisition and colonisation resistance — both articles converge on the inadequacy of reductionist models for explaining microbiome outcomes. It parallels [§72] in examining how external perturbations (here, dietary antimicrobial exposure; there, bariatric surgery) trigger microbiota remodelling, but the present article foregrounds resistance gene ecology rather than metabolic consequences. The food-microbiome interaction angle also parallels [§89], which examines how a modified dietary intervention shapes gut microbial metabolism in a clinical population, illustrating that diet composition has measurable microbiome effects — a premise central to the AMR risk framing here. More broadly, the review's emphasis on dysbiosis-permissive conditions for pathobiont or resistance-gene establishment resonates with [§139], which documents how gut microbiota dysbiosis remodels host transcriptional landscapes, underscoring that community-level disruptions have consequences well beyond the gut lumen itself.

• The human microbiome at translational crossroads: an ecological and causal perspective
  Directly complementary framing: both tackle microbiome complexity and causal inference, but [id=100] provides the ecological and translational theory that underpins the ARG-transfer mechanisms reviewed here.
• Microbiota remodeling after bariatric surgery: Procedure-specific dynamics and metabolic implications
  Useful contrast in perturbation type — surgical microbiota remodelling versus dietary ARG exposure — allowing readers to compare how different external shocks alter community composition and what that implies for resistance dynamics.
• Effects of processed low-protein brown rice on patients with chronic kidney disease
  Concrete dietary-intervention data showing measurable gut microbiome shifts from a specific food modification, providing the kind of in vivo human evidence the AMR review identifies as critically lacking in its own field.
• Gut Microbiota Dysbiosis Remodels the Multi-Tissue Transcriptional Landscape of the Host
  Extends the consequences of dysbiosis beyond ARG carriage to multi-tissue transcriptional remodelling, helping readers appreciate the systemic stakes of the gut community disruptions discussed in the AMR review.
• Schistosoma mansoni infection is associated with changes in gut microbiota in preschool age children in Albertine Region, Uganda
  Offers a real-world example of how an environmental/infectious exposure (Schistosoma infection) reshapes gut microbiota composition, illustrating how non-dietary ecological pressures interact with the same community-stability principles central to ARG colonisation resistance.