Evolution at the Host-Pathogen Interface: Mechanistic Insights into Antimicrobial Resistance

Abstract

The rapid global rise of antimicrobial resistance (AMR) represents a critical threat to modern medicine, undermining the effective treatment of infectious diseases and challenging long-standing therapeutic advances. This review adopts an integrative, mechanistic perspective to examine how microbial adaptation drives resistance development, persistence, and dissemination across clinical and ecological contexts. Core resistance mechanisms include target site modifications, enzymatic drug inactivation, altered membrane permeability, and activation of multidrug efflux systems, which are further amplified by horizontal gene transfer mediated through plasmids, transposons, and bacteriophages. Biofilm formation constitutes a critical phenotypic strategy that enhances antimicrobial tolerance by promoting metabolic heterogeneity, restricted drug penetration, and the survival of persister cells. In parallel, pathogens employ diverse immune evasion strategies, including antigenic variation, immune modulation, and intracellular persistence, prolonging infection and sustaining selective pressure for resistance evolution. Environmental reservoirs of antimicrobial residues and resistance genes originating from clinical, agricultural, and industrial sources further expand the global resistome, underscoring the interconnected nature of AMR across human, animal, and environmental domains. Recent advances in genomics, transcriptomics, proteomics, metabolomics, and systems biology have transformed understanding of resistance pathways and host–pathogen dynamics. Integrating these mechanistic insights within a One Health framework is essential for informing antimicrobial stewardship, guiding innovative therapeutic strategies, and preserving the long-term effectiveness of antimicrobial agents.