Non-Tuberculous Mycobacteria at the Human-Animal-Environment Interface: Antimicrobial Resistance, Environmental...

Non-tuberculous mycobacteria (NTM) are increasingly recognized as important opportunistic pathogens at the human-animal-environment interface. Their growing relevance is driven by increasing disease burden, environmental persistence, occurrence in multiple animal hosts and complex antimicrobial resistance (AMR) patterns. Unlike classical zoonotic pathogens, most NTM are primarily acquired from shared environmental reservoirs rather than through sustained host-to-host transmission. This review examines NTM from a One Health perspective, focusing on AMR, ecology, animal occurrence, cross-species exposure and public health relevance.

A narrative review of the current literature was conducted to synthesize evidence on the ecology, environmental reservoirs, occurrence in animals, transmission patterns and AMR mechanisms of NTM. Particular attention was given to studies addressing the human-animal-environment interface and the implications of NTM for One Health surveillance and risk assessment.

The reviewed literature shows that NTM are widely distributed in water, soil, sediments and biofilms, creating repeated opportunities for exposure in both animals and humans. They have been reported in livestock, wildlife, companion animals, reptiles and aquatic organisms, where they may act as colonizers, opportunistic pathogens, or sources of diagnostic interference. Evidence for direct animal-to-human transmission remains limited, but animal and environmental findings are important for understanding ecological overlap, host range and circulation of resistant strains. AMR in NTM is shaped by intrinsic resistance, acquired mutations, efflux activity, and biofilm-associated tolerance, which together complicate treatment and resistance prediction.

NTM should be considered environmentally maintained, multi-host organisms of increasing One Health importance rather than conventional zoonotic pathogens. Improved interdisciplinary surveillance, diagnostics and research are needed to clarify exposure pathways, resistance development and public health risk.