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Ambient temperature variations and antimicrobial resistance: a multicountry analysis of non-linear relationships and temperature thresholds

Chimera readability score 92 out of 100, Quantum Electrodynamics reading level.

Introduction
Antimicrobial resistance (AMR) is an escalating global crisis, posing significant threats to human health and socioeconomic stability. Since the discovery of penicillin in 1928, antibiotics have dramatically reduced mortality from infectious diseases and transformed medical practice. However, the extensive misuse and overuse of antibiotics have accelerated the development of resistance among pathogens, undermining treatment efficacy, increasing treatment failures and significantly amplifying the global disease burden.1 According to the WHO, AMR currently results in approximately 700 000 deaths annually, a figure that could rise to 10 million by 2050 if effective measures are not implemented.2 This alarming trend not only intensifies the burden on global healthcare systems but also inflicts severe economic consequences. For example, in the European Union, AMR causes over 25 000 deaths annually, incurring €1.5 billion in direct healthcare costs and productivity losses.3 In the USA, the economic impact of AMR amounts to US$55 billion annually.4 Furthermore, AMR increases the cost and complexity of treating infections such as pneumonia, urinary tract infections and tuberculosis, leading to prolonged hospital stays and greater societal burdens.5 Critically, AMR is a global issue, with resistance genes spreading across borders through humans, animals and the environment.6 The WHO’s Global Antimicrobial Resistance Surveillance Report highlights that AMR has reached alarming levels in many countries, further exacerbating this pressing public health challenge.7
As global temperatures continue to rise, with projections of 1.5°C–4.5°C increases by the end of this century, emerging research increasingly highlights the role of climate change in shaping AMR patterns.8 9 Rising temperatures can influence pathogen distribution, alter antibiotic efficacy and accelerate the spread of resistance genes, posing a new global public health threat.10 Current evidence demonstrates that ambient temperature is a key determinant of bacterial growth and reproduction kinetics. Elevated environmental temperatures can accelerate pathogen metabolism and proliferation, thereby enhancing their survival rates in both environmental reservoirs and host organisms.11 For instance, an experimental study on various pathogens found that for every 1°C increase in temperature, the growth rate of certain resistant bacteria could rise by 10%–15%.12 This accelerated growth potentially facilitates more rapid dissemination of resistance genes within bacterial populations, thereby increasing the probability of antibiotic treatment failure. Furthermore, temperature shifts can fundamentally alter competitive dynamics among bacterial species, potentially favouring the dominance of more resistant strains in natural environments.13 Temperature variations may also exacerbate AMR development by modifying the stability and degradation profiles of antibiotics in environmental matrices. Research indicates that certain antimicrobial compounds degrade more rapidly under elevated temperature conditions, reducing their persistence and efficacy in the environment.8 This phenomenon not only potentially compromises treatment outcomes but may also expand the environmental prevalence of sublethal antibiotic concentrations, creating selective conditions favourable for resistance emergence and proliferation.14
The interplay between climate change and AMR is further complicated by extreme weather events such as floods and droughts, which may indirectly influence AMR dissemination by altering the concentration and hydrological transport of antibiotics and resistance genes in aquatic ecosystems.15 For instance, floods can cause sewage treatment systems to overflow, directly discharging wastewater containing high concentrations of antibiotics and resistance genes into environmental water bodies, thereby accelerating the spread of resistance.16 Climate change may additionally impact AMR through its influence on human behavioural patterns and disease epidemiology. As temperatures increase, the geographical distribution and prevalence of certain infectious diseases may expand, potentially leading to increased antimicrobial consumption (AMC) and consequently intensifying selective pressure for resistance development.17 The expanded transmission range of vector-borne diseases such as dengue fever exemplifies this concern, as it may necessitate increased antibiotic usage, thereby creating additional opportunities for resistance evolution.18
Despite growing attention to the potential impact of climate change on AMR, existing studies have notable limitations. Most research has been geographically limited, typically focusing on specific countries or regions, making it difficult to capture global trends.19 Additionally, many studies involve short time spans, failing to adequately assess the long-term impact of climate change on AMR.6 8 15 More importantly, current research predominantly employs linear models to analyse the relationship between temperature and AMR, potentially overlooking non-linear relationships and critical temperature thresholds.8 Simple linear analyses may underestimate the actual impact of temperature on AMR, especially under extreme climate conditions.20 Furthermore, the relationship between temperature and AMR may be moderated by other environmental and socioeconomic factors, such as air quality, water resource management and population density.8 15 21 22 These complex interactions highlight the need for larger-scale, more systematic studies.
In this study, we conducted a longitudinal analysis of data spanning 24 years (1999–2022) from 56 countries and territories worldwide, employing segmented regression models to characterise the non-linear relationships between ambient temperature and AMR patterns. Our primary objective was to describe temperature thresholds at which the association between temperature and resistance patterns shifts significantly, while accounting for relevant socioeconomic and environmental covariates. By elucidating these complex relationships, our findings provide descriptive insights relevant to understanding AMR patterns under projected climate change scenarios and informing public health strategies to address this growing global threat.

Sentinel — Human

Confidence

The text functions as a high-level scientific literature review, effectively synthesizing established AMR data with emerging climate change hypotheses and acknowledging the limitations of current modeling, typical of human academic writing.

Signals Detected
low severity: Moderate sentence length variance and nuanced vocabulary.
low severity: Strong thematic flow connecting macro-level crisis to specific mechanistic links (temperature, growth kinetics, environmental dispersion).
low severity: Appropriate citation integration and structural progression typical of academic synthesis.
low severity: Claims are supported by referencing established scientific concepts (pathogen kinetics, degradation) and cite specific types of empirical analysis limitations.
Human Indicators
The structure moves fluidly from establishing a known crisis (AMR statistics) to introducing an emerging complicating factor (climate change), then detailing the biological mechanisms, and finally critiquing existing research limitations before presenting a study objective. This argumentative trajectory is complex.
The inclusion of specific references to experimental findings (e.g., 1°C increase leading to 10%–15% growth rate rise) interwoven with broader public health context suggests synthesis from multiple, dense sources.