Diagnostics for priority bacterial pathogens: global gaps and research needs for curbing antimicrobial resistance in low-resource settings.

Antimicrobial resistance (AMR) is a major and growing threat to global health, development, and security, with the greatest burden borne by low-income and middle-income countries (LMICs). Without urgent intervention, cumulative deaths between 2020 and 2050, attributable to AMR, are projected to be 39·1 million globally. Effective diagnostics are important to bacterial pathogen detection and antimicrobial susceptibility testing, and such diagnostics support antibiotic stewardship by reducing adverse drug events (eg, toxicity or allergy) and restricting the emergence and spread of AMR. Yet, access to appropriate diagnostics in LMICs remains constrained. This Review summarises the current landscape of commercial and pipeline bacterial in-vitro diagnostics, drawing on the updated WHO 2024 Bacterial Priority Pathogen List, the 2025 WHO diagnostic landscape analysis, and the WHO Diagnostic Initiative, which has four pillars, one of which focuses on research and innovation to improve diagnostics for AMR. We discuss phenotypic and non-phenotypic testing approaches, assess platform suitability across health system tiers in LMICs, and outline WHO priorities for the next 3-5 years to guide innovation and improve equitable access. Although multiple commercial platforms exist for bacterial identification and susceptibility or resistance testing, most platforms are infrastructure-intensive and confined to regional or reference laboratories, leaving major diagnostic gaps at primary and secondary care levels. Promising advances include rapid immunoassays and emerging molecular platforms; however, no simple, affordable, decentralised solution provides reliable identification and susceptibility or resistance testing for key bacterial priority pathogens.