Climate change and antimicrobial resistance in the Western Pacific: a mixed-methods systematic analysis

Climate change and antimicrobial resistance (AMR) are escalating public health threats globally. The Western Pacific Region faces unique climatic and socioeconomic vulnerabilities, but evidence on this climate-AMR intersection is limited. We aimed to systematically provide evidence on this critical issue.

We conducted a three-stage mixed-methods systematic analysis: (1) a narrative review mapping the regional AMR landscape and summarizing potential climate-driven mechanisms; (2) a systematic review (PubMed and Google Scholar, January 2000-March 2025) of regional quantitative studies; and (3) an empirical quantitative analysis using a longitudinal panel dataset. This analysis completes our systematic approach by visualizing AMR mortality trends (using data from the GRAM project) and applying regression analysis to model AMR-attributable death rates based on climatic and socioeconomic factors, providing quantitative evidence of the regional situation and its potential drivers.

Literature review evidence showed that increasing temperature caused by climate change directly accelerates bacterial growth and resistance mutation rates and indirectly affects healthcare disruptions and antibiotic misuse during extreme weather events. We included 18 quantitative studies synthesised using the SWiM framework, which provided more specific evidence that higher temperatures are associated with increased clinical resistance rates and enhanced environmental dissemination of antibiotic resistance genes (ARGs). Our quantitative analysis found that a 1 °C increase in mean ambient temperature was associated with higher AMR-attributable mortality from carbapenem-resistant Acinetobacter baumannii (CRAB; β = 0.652, 95% CI 0.579-0.724, p < 0.001) and carbapenem-resistant Pseudomonas aeruginosa (CRPA; β = 0.422, 95% CI 0.304-0.541, p < 0.001). It also revealed that socioeconomic factors have heterogeneous effects.

Climatic conditions and socioeconomic vulnerabilities jointly shape AMR risks in the Western Pacific Region. Projected increases in extreme weather events threaten to strain healthcare systems further and worsen antibiotic misuse. Strengthening climate-resilient health systems, improving multisectoral AMR governance, and establishing integrated AMR-climate surveillance networks are essential regional priorities.

This work is supported by World Health Organization (WPRO/2024-02/AGE-DHP/22552 4), National Natural Science Foundation of China (82422064, 82250610230, 72374228, 72074234), Natural Science Foundation of Beijing (IS23105), National Bureau for Disease Control and Prevention (20241660047), Guangzhou Basic and Applied Basic Research Program, China (2025A04J5118), Fundamental Scientific Research Funds for Central Universities, China (SYSU-25wkjc02), National Major Science and Technology Project of China (No. 2024ZD0524500), and Singapore National Medical Research Council (CoSTAR-HS CG21APR2005; AMRITS MOH-001326-01).