The climate crisis and antibiotic resistance are increasingly emerging as intertwined phenomena, no longer separable on environmental and health grounds. Rising temperatures, more frequent droughts, and altered rainfall are changing microbial communities and fostering conditions in which bacteria evolve drug defense mechanisms more rapidly. Recent research indicates measurable increases in resistance genes and an accelerated evolutionary dynamic in bacteria, with signals extending from agricultural soils to hospitals in numerous countries.
CLIMATE CRISIS AND RISING ANTIMICROBIAL RESISTANCE
A large international analysis detected an approximately 10% increase in antibiotic resistance genes in salmonella between 1940 and 2023, based on over 480,000 samples collected in 139 countries. The study, published in The Lancet Planetary Health, describes the climate crisis as a factor accelerating the global spread of antimicrobial resistance, emphasizing that the effect does not follow a linear trend but depends on the interaction between temperature and precipitation.
According to the authors, rising temperatures and changes in climate patterns “non-linearly amplify the abundance and spread of antimicrobial resistance genes in pathogenic bacteria.” It is also highlighted that climate change reduces the ecological stability of microorganisms and accelerates the evolutionary processes of resistance in different environments.
DROUGHT AS AN EVOLUTIONARY DRIVER IN SOILS
A second line of research, published in Nature Microbiology, identifies drought as a direct factor in the increase of antimicrobial resistance in soils. Arid conditions alter soil structure, concentrating natural antimicrobial substances and increasing competition among bacteria.
In dry environments, water fragments into small isolated spaces, resources decrease, and microorganisms enter a phase of intense competition. Under these conditions, antibiotic production increases along with the selection of bacteria capable of resistance. Microbial communities also tend to be dominated by specialized groups, particularly belonging to Actinobacteriota, with a strong presence of the genus Streptomyces.
Researchers observed that seasonal and climatic variations directly influence soil microbiome composition, making drought a key factor in their evolution.
MICROBIOLOGICAL DYNAMICS AND NATURAL SELECTION
When soil loses moisture, researchers explain, the concentration of natural antibiotics increases, turning the environment into a highly selective space. More sensitive bacteria are eliminated, while those equipped with resistance genes survive and spread.
Analyses show that genes related to antibiotic production become more abundant after drought periods and decrease when conditions return to wet, indicating a dynamic system regulated by climatic cycles. This process contributes to a continuous reorganization of microbial communities on a global scale.
FROM SOIL TO HOSPITALS
A central element emerging from the studies concerns the connection between natural environments and healthcare systems. Data analysis from 116 countries shows that greater local aridity is associated with an increase in resistant infections in hospital settings.
In several cases, resistance genes identified in soil bacteria are identical to those found in clinical pathogens such as Enterococcus faecium, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa, organisms known for their ability to survive antibiotic treatments.
GENETIC TRANSFER AND EVOLUTIONARY NETWORKS
A decisive role is then played by horizontal gene transfer, through which bacteria can exchange resistance genes. This mechanism allows the transfer of traits developed in the natural environment to pathogens affecting humans, creating a continuous evolutionary network between soil and clinical organisms.
Studies highlight that drier soils present a greater abundance of both resistance genes and genes related to antibiotic production, signaling a constant evolutionary pressure observed in ecosystems distributed across Asia, Europe, and North America.
AN INTERCONNECTED SYSTEM OF HEALTH AND ENVIRONMENT
Research describes a scenario in which climate, environment, and human health are closely linked. Increasing drought contributes to expanding the natural reservoir of antimicrobial resistance, with possible repercussions on the global spread of infections.
In this context fits the “One Health” model, which interprets health as a single system involving humans, animals, and the environment because, as reported in one of the studies, “no place is immune,” indicating the speed with which pathogens can spread on a global scale.
