In a recent study published in The Lancet Planetary Health, researchers explore the role of particulate matter within the environment to facilitate the spread of genetic elements responsible for antibiotic resistance.
Study: Association between particulate matter (PM)2·5 air pollution and clinical antibiotic resistance: a global analysis. Image Credit: Kodda / Shutterstock.com
Antibiotic resistance remains an urgent public health issue, as millions of people die every year as a result of bacterial infections caused by pathogens that have become resistant to multiple antibiotics. In 2019, about 1.3 million deaths were attributed to antibiotic resistance, which is almost double the estimated number that was reported in 2016.
Antibiotic resistance is the result of the overuse and misuse of antibiotics. Notably, the genes responsible for antibiotic resistance are transferred between bacteria. Both these genes and resistant bacteria can spread rapidly throughout the world, as well as across species and ecosystems.
Antibiotic resistant bacteria and genes are commonly isolated from hospitals and livestock farms, where they subsequently enter the sewage systems and other parts of the ecosystem, including the air.
Air is the primary route for atmospheric dissemination of antibiotic resistance, with fine particulate matter 2.5 (PM2.5) known to contain multiple types of these bacteria and genes. PM2.5 alone may permeabilize the cell membrane, thus facilitating the efficient transfer of antibiotic resistance genes between bacteria. This can contribute to the more rapid exchange of these elements and ultimately accelerate the evolution of more deadly antibiotic resistance elements.
The aim of the current study was to provide quantitative evidence of how PM2.5 affects antibiotic resistance. To this end, data from over 11.5 million cultured isolates were obtained, with 43 types of antibiotics being tested against nine pathogens including Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli.
What did the study show?
A significant association of PM2.5 was observed with antibiotic resistance throughout various regions of the world. This relationship was consistently seen with most antibiotic-resistant bacteria, with a time-dependent increase in the strength of association.
PM2.5 is the single most important factor in antibiotic resistance, as it outweighs the effects of antibiotic use, drinking water provision, and current health expenditure. The abundance of antibiotic resistance genes in PM2.5 is higher than in soil, rivers, sediments, and some treatment systems.
For example, with K. pneumoniae, a rise by 1% in PM2.5 was associated with a rise of 1.5% in carbapenem resistance. Aminoglycoside resistance showed a similar rise, while resistance to multiple other commonly used antibiotics such as amoxycillin-clavulanate, fluoroquinolones, polymyxins, and third-generation cephalosporins increased by 0.6-1.4%.
Rising antibiotic resistance was due to the acquisition of resistance elements through PM2.5. In 2018, this accounted for about 500,000 premature deaths, which amounts to a loss of almost 18 million years of life worldwide. In terms of welfare expenditure, the financial consequence of antibiotic resistance is estimated at $400 billion USD each year.
Overall, each unit of rise in PM2.5 could lead to an increase in antibiotic resistance by 0.43%, which is comparable to the rise of 0.48% per unit increase in antibiotic use. PM2.5 was among the primary drivers of antibiotic resistance, as it accounted for about 11% of variations.
In north Africa and west Asia, antibiotic resistance rose to about 20%. These continents currently have the highest rates of antibiotic resistance and are also likely to suffer the most from rising PM2.5 levels.
China and India could be the countries where changes in PM2·5 have the largest effect on premature deaths attributable to antibiotic resistance due to their large populations.”
The World Health Organization (WHO) has set an air quality standard that recommends no more than five μg/m3 of PM2.5. If countries throughout the world achieve this standard by 2050, the global prevalence of antibiotic resistance will likely decrease by about 17%, in addition to preventing about 25% of premature deaths and yearly savings of about $640 billion USD.
Without intervention, antibiotic resistance will increase by an estimated 17%, with annual deaths from resistant infections also rising to 56%, which amounts to about 0.84 million deaths in 2050.
Importantly, various interventions have successfully reduced the adverse outcomes associated with antibiotic resistance. Some of these measures include doubling the current health expenditure, reducing current antibiotic use by at least 50%, achieving WHO-standard PM2.5 levels, and providing universal access to basic drinking water.
What are the implications?
This pioneering analysis of how PM2.5 levels affect clinical antibiotic resistance throughout the world demonstrates a consistent rise in antibiotic resistance with increasing PM2.5 levels. These findings may support the development of novel strategies to control antibiotic resistance from an ecological perspective.
Our results highlight that controlling air pollution to reduce PM2·5 concentrations might lead to substantial health and economic benefits by reducing antibiotic resistance.”