The power of resistance: mechanisms of antimicrobial resistance in Mycobacterium tuberculosis and its impact on tuberculosis management

SUMMARYThe global resurgence of drug-resistant tuberculosis (DR-TB) presents a formidable challenge to public health, driven by a complex interplay of mycobacterial evolution, dynamics and outcomes of host-pathogen interactions and systemic gaps in diagnosis and treatment strategies. This comprehensive review delineates the multifactorial basis of antimicrobial resistance (AMR) in Mycobacterium tuberculosis (Mtb), integrating molecular, immunological, and pharmacological perspectives to inform next-generation strategies for effective TB control. We reconceptualize TB as a dynamic clinical spectrum-ranging from asymptomatic infection to overt disease-shaped by granuloma biology and bacterial adaptation. This spectrum underpins both diagnostic ambiguity and therapeutic failure, particularly in the context of phenotypic drug tolerance/resistance to current anti-TB drugs. We discuss Mtb's intrinsic and extrinsic resistance mechanisms, including the lipid-rich cell envelope, efflux systems, and enzymatic drug modification, which are compounded by acquired mutations that disrupt drug activation, alter targets, and confer cross-resistance. These adaptations are further potentiated by granuloma-induced pharmacokinetic heterogeneity and host-induced metabolic quiescence. We highlight the emerging role of therapeutic drug monitoring and pharmacokinetic/pharmacodynamic modeling in optimizing individualized therapy, particularly for novel regimens incorporating bedaquiline, pretomanid, and linezolid. Moreover, we underscore the diagnostic limitations in detecting heteroresistance and early-stage disease, advocating for expanded deployment of advanced and targeted molecular diagnostic modalities. Finally, we propose a paradigm shift toward integrated, precision-based TB management, leveraging host-directed therapies, biofilm-disrupting agents, and real-time pharmacokinetics-guided dosing to preempt resistance emergence and improve clinical outcomes. This review provides a translational framework for addressing the biological and operational complexities of DR-TB in the era of AMR.