Drug-resistant killer bugs linked to air pollution, top scientists say

As if air pollution wasn’t deadly enough.

Now new research suggests tiny airborne pollutants may be linked to higher rates of drug-resistant lethal bacteria.

In the study, researchers from Zhejiang University, China and the University of Cambridge, England, concluded that air pollution is one of the leading factors driving antimicrobial resistance (AMR) after compiling data from 116 countries between 2000 and 2018, with more than 11.5 million lab test results covering nine bacterial pathogens and 43 types of antibiotics.

The world is battling to combat the growing threat from antimicrobial resistance — a phenomenon caused by bugs such as bacteria, fungi and parasites evolving to survive against drug treatments. Without effective antibiotics, routine operations and previously minor infections, for example, could once again turn deadly.

“Our analysis presents strong evidence that increasing levels of air pollution are associated with increased risk of antibiotic resistance,” said the authors of the study, published Tuesday in The Lancet Planetary Health.

Scientists previously found inhaling tiny particulate matter — typically generated from industrial processes, road transport, coal and wood burning — to be one way to be infected with a drug-resistant bug. That’s because the matter, known as PM2.5, contains diverse antibiotic-resistant bacteria and antibiotic-resistance genes.

With around 1.3 million deaths in 2019 directly attributed to antimicrobial resistance, researchers set out to identify the extent to which air pollution may be fueling this global crisis.

The misuse and overuse of antibiotics are the main drivers of antibiotic resistance, but the scientists found that every 1 percent rise in air pollution was linked with increases in antibiotic resistance of between 0.5 and 1.9 percent, depending on the pathogen. And this association has strengthened over time. Overall, they concluded that pollution accounted for 11 percent of the global growth in AMR.

“Antibiotic resistance and air pollution are each in their own right among the greatest threats to global health,” said lead author Hong Chen, of Zhejiang University. “Until now, we didn’t have a clear picture of the possible links between the two, but this work suggests the benefits of controlling air pollution could be two-fold: not only will it reduce the harmful effects of poor air quality, it could also play a major role in combatting the rise and spread of antibiotic-resistant bacteria.”

Their analysis indicates antibiotic resistance resulting from air pollution is linked to an estimated 480,000 premature deaths in 2018, with an additional economic cost of $395 billion based on the years of life lost in each country.

Their modeling suggests meeting World Health Organization air quality guidelines by 2050 could reduce bugs’ antibiotic resistance by 17 percent and prevent 23 percent of associated premature deaths, delivering annual economic savings of $640 billion.

“The findings have substantial policy and environmental implications by presenting a new pathway to combat clinical antibiotic resistance by controlling environmental pollution,” wrote the study authors.

More work needed

But not everyone is on board with these conclusions.

While the researchers adjusted their results to account for some potential confounding factors, such as the overall level of antibiotic use in each country, the availability of clean water and educational measures, other potential factors were not accounted for, according to Kevin McConway, emeritus professor of applied statistics at the Open University.

Therefore, it’s not certain changes in air pollution levels cause changes in antibiotic resistance, said McConway, because “it’s still possible that there are confounding factors at work, and that these are involved in the causation of a country’s level of antibiotic resistance.”

In addition, known factors that drive antibiotic resistance were not examined in the study, pointed out Anna Hansell, professor of environmental epidemiology at the University of Leicester. “These may be important determinants of antibiotic resistance in countries that also have higher air pollution levels,” she said.

McConway cautioned against drawing conclusions from the authors’ modeling. That’s because it’s based on an observational study that has shown a correlation as opposed to cause and effect, he said.

This research “has not shown to any degree of certainty that making these changes (to PM2.5 levels) would reduce antibiotic resistance in the way that the scenario modelling says it would,” he added.

The authors acknowledge several limitations of the study, including that many lower-income countries lack good data, and that countries cannot be directly compared given differences in testing for example. They also call for further studies to verify the underlying mechanism of air pollutants affecting antibiotic resistance, which is “still unclear.”