Infectious Disease · Medical Literature
[Review] Diagnostics for priority bacterial pathogens: global gaps and research needs for curbing antimicrobial resistance in low-resource settings
Abstract
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.
Clinical relevance
What are the current landscape, critical gaps, and WHO-defined research priorities for bacterial in-vitro diagnostics—including pathogen identification and antimicrobial susceptibility testing—needed to curb antimicrobial resistance in low- and middle-income countries? __SNAPSHOT__ {"studyDesign":"Narrative/structured review incorporating desktop review of publicly available data, systematic literature review, and expert consultations","setting":"Global scope; WHO AMR Department and international co-investigators; focus on low- and middle-income countries (LMICs) across all health system tiers (community/outreach through national reference laboratories)","sampleSize":"Not applicable (review article; no primary patient population enrolled)","population":"Populations in LMICs affected by infections caused by WHO 2024 Bacterial Priority Pathogens; all health system tiers from primary care to national reference laboratories","intervention":"Comprehensive assessment of commercially available and pipeline bacterial in-vitro diagnostics: phenotypic methods (culture, broth microdilution, disc diffusion, antimicrobial gradient diffusion, semiautomated and fully automated platforms) and non-phenotypic/genotypic methods (PCR, LAMP, DNA microarrays, next-generation sequencing)","comparator":"Not applicable (single-arm descriptive review; comparative suitability assessed across health system tiers rather than between patient groups)","primaryOutcome":"Identification of diagnostic gaps and research priorities for bacterial pathogen detection and antimicrobial susceptibility testing in LMICs, aligned with the WHO 2024 Bacterial Priority Pathogen List and the 2025 WHO diagnostic landscape analysis","followUp":"Not applicable (review article; no longitudinal patient follow-up)","fundingSource":"Not reported in the provided abstract; senior co-authors affiliated with WHO AMR Department, Geneva; note that some authors are declared consultants to the WHO AMR Division"}
Key findings
No original quantitative outcome data (e.g., sensitivity, specificity, NNT, p-values, confidence intervals) are reported in the provided abstract; this summary is based solely on the abstract and publicly available structured content from the full article. Key narrative findings are as follows: (1) AMR Burden: Cumulative AMR-attributable deaths between 2020 and 2050 are projected at 39.1 million globally (Global Burden of Disease Study 2024), with an additional 169 million lives potentially lost indirectly from AMR-associated complications—figures reported descriptively, not generated by this review. (2) Diagnostic Landscape: Multiple commercial platforms exist for bacterial identification and antimicrobial susceptibility testing; however, most are infrastructure-intensive and confined to regional or national reference laboratories, leaving major diagnostic gaps at primary and secondary care levels in LMICs. (3) Phenotypic AST Methods: Among standardized methods recognized by CLSI and EUCAST (broth microdilution, disc diffusion, antimicrobial gradient diffusion), Kirby–Bauer disc diffusion is identified as the most widely used method in clinical microbiology laboratories and is deemed suitable for LMICs given its low cost and ease of use, despite providing only qualitative results and lacking quantitative minimum inhibitory concentration values. Automated and semiautomated systems used in high-income countries remain largely unavailable in LMICs and are further constrained by dependence on cultured isolates and reduced diagnostic yield when prior antimicrobial exposure suppresses organism growth. (4) Non-Phenotypic Methods: Genotypic methods (PCR, LAMP, DNA microarrays, and others) can detect genetic determinants of resistance; however, their LMIC suitability, cost-effectiveness, and implementation barriers are discussed qualitatively. (5) WHO Priorities: The review outlines WHO priorities for the next 3–5 years to guide diagnostic innovation and improve equitable access, aligned with the WHO Diagnostic Initiative. No effect sizes, comparative diagnostic accuracy statistics, or NNT/NNH values are calculable from the abstract alone.
Practice implications
IMPORTANT LIMITATION: Only the published abstract and structured excerpts from the full article were available for this summary; the complete data tables, figures, and supporting analyses from the full review were not accessible. Findings should be interpreted accordingly. This WHO-affiliated structured review establishes that existing bacterial diagnostics for AMR—while commercially mature in high-income settings—are functionally inaccessible at the point of care in LMICs, where the AMR burden is greatest. The review explicitly addresses the WHO 2024 Bacterial Priority Pathogen List (24 antibiotic-resistant pathogens across 15 families) and is designed to inform R&D investment and policy over the next 3–5 years. The findings apply most directly to health systems planners, diagnostic developers, funders, and policy makers rather than to individual clinical prescribing decisions. The review does not establish the clinical impact of specific diagnostic interventions on patient outcomes (e.g., mortality, length of stay, antibiotic appropriateness rates), nor does it provide head-to-head diagnostic accuracy comparisons between platforms in LMIC conditions. Populations not adequately represented include pediatric subpopulations, neonates, immunocompromised patients, and populations in conflict or displacement settings—recognized knowledge gaps within the broader WHO AMR research agenda. The observation that AMR surveillance data are deficient in LMICs due to inadequate laboratory capacity is a well-established structural finding confirmed by multiple independent sources and is not novel to this review; however, the synthesis within the framework of the updated WHO priority pathogen list and the 2025 landscape analysis gives it current policy relevance. Practice should not change based on this review alone; it serves as a roadmap for future diagnostic development and procurement strategy. __LIMITATIONS__ 1. Study Design: Narrative/structured review methodology; no systematic meta-analysis, PRISMA framework, or formal GRADE assessment of evidence quality is described. 2. Abstract-Only Access: Full data tables, diagnostic accuracy metrics, platform comparisons, and detailed methodology were not available for this summary—a critical limitation of this teaching document. 3. WHO Affiliation: Majority of authors are affiliated with or serve as consultants to the WHO AMR Department; while appropriate for a WHO-commissioned review, this represents a potential source of institutional perspective bias. 4. Lack of Primary Outcome Data: No patient-level clinical outcomes (mortality, treatment success, time-to-appropriate-antibiotic) are reported; the review addresses availability and suitability of platforms, not their measured impact on clinical endpoints. 5. Generalizability: LMIC health system tiers vary enormously by country and region; findings may not be uniformly applicable across sub-Saharan Africa, South Asia, Latin America, and the Pacific without context-specific adaptation. 6. Surrogate Focus: Diagnostic availability and platform suitability are used as proxies for AMR containment impact; the link between improved diagnostics and patient outcomes or population-level AMR burden reduction is assumed but not quantified in this review. 7. Rapidly Evolving Field: The diagnostic pipeline landscape changes rapidly; findings reflecting 2024–2025 data may require reassessment within 2–3 years. 8. Selection Bias in Sources: Desktop review methodology relying on published reports from recognized health organizations may underrepresent grey literature, negative studies, or platform failures from LMIC implementation experience. __BOTTOM_LINE_CATEGORY__ potentially_practice_informing __BOTTOM_LINE__ This WHO-affiliated review confirms that while commercial bacterial diagnostic platforms for identification and antimicrobial susceptibility testing are mature in high-income settings, they remain infrastructure-intensive and largely inaccessible at primary and secondary care levels in LMICs—precisely where the AMR burden is highest. Kirby–Bauer disc diffusion remains the most feasible phenotypic AST method for resource-limited settings, but culture-independent, rapid, and affordable alternatives are urgently needed across the health system hierarchy. Clinicians and health systems leaders in LMICs should advocate for procurement of fit-for-purpose diagnostics aligned with WHO priority pathogen lists, while awaiting the next generation of point-of-care platforms currently in the development pipeline.