Skip to content

This is new. Remember us telling you about the antibiotic-resistant bacteria found in supermarket meats a few weeks ago? Well, now it seems those little buggers have figured out how to go global — by hitching a ride on clouds. 

Researchers from Université Laval in Quebec and Université Clermont Auvergne in France showed, for the first time, that bacteria carrying antibiotic-resistant genes can be harbored and carried in the atmosphere.

A new study has found that bacteria resistant to antibiotics can not only live on the surfaces of plants or within the soil, but they can also survive in clouds, meaning they can travel thousands of miles and potentially invade new environments. 

“Considering that the atmosphere is a system that is pretty harsh for the bacteria, (the number they found) is quite a lot, actually,” said Florent Rossi, first author of the study and postdoctoral fellow at Université Laval’s Faculty of Science and Engineering.

Antimicrobial resistance genes are a naturally occurring phenomenon everywhere in nature, he explained, adding that the scientific community has long known that these genes can exist in the air (which can be carried from the ground to the atmosphere by the wind).

However, “what we didn’t know is how high they can be and how far they can travel. And the fact that we found them in clouds highlights that they can travel for long distances,” Rossi stated.

The rise of antibiotic-resistant bacteria has made it more and more challenging to effectively treat a developing number of bacterial infections, including pneumonia, tuberculosis, and foodborne illnesses. This trend has resulted in longer hospitalizations, higher medical expenses, and elevated mortality rates, according to the World Health Organization (WHO).

Antibiotic resistance has become so prevalent that the WHO has classified it as one of humanity’s 10 global public health threats.

Because of its prevalence in nature, Rossi and his team wanted to understand how far antibacterial resistance genes can travel.

The researchers sampled clouds at the Puy de Dôme summit, a dormant volcano in south-central France. Working from an atmospheric research station 1,465 meters (4806 feet) above ground, scientists conducted 12 cloud sampling sessions over two years using high-flow rate “vacuums.” 

After reviewing these samples, the team found they contained about 8,000 bacteria per milliliter of cloud water, on average. The study found between 5-50% of these bacteria could be alive and potentially active.

It’s unclear exactly how far the antibiotic-resistant genes can travel. Still, because clouds can be as far up as six kilometers (3.7 miles) into the sky, Rossi estimated they can spread “over thousands of kilometers.”

“We don’t know whether the bacteria in the atmosphere can grow when it lands in soil when it rains, and we don’t know if those bacteria can spread their antimicrobial resistance genes,” Rossi added.

According to a 2022 report by the Public Health Agency of Canada (PHAC), antibiotics are used for medicine, but mainly in agriculture, to prevent disease and to improve growth production. The agency estimated that in 2020, 82% of all antibiotics used in Canada were related to livestock.

As the use of antibiotics increases, bacteria can develop resistance to one or more of them, explained Brian Conway, medical director of the Vancouver Infectious Disease Centre. The problem will get worse if antibiotics are used inappropriately for extended periods. As a result, bacteria can evolve to become resistant to multiple antibiotics.

Because of the risk, Conway believes the Université Laval’s study is crucial in highlighting “another way in which these bacteria can spread from one location to another.” But, he warns, “Perhaps it teaches us that in places where there haven’t necessarily been cases of antibiotic-resistant bacteria that have spread from one person to another, this is a way in which they could be introduced into an environment.”

The study, he stressed, emphasizes the importance of minimizing the rise of antibiotic-resistant bacteria, which he hopes can be achieved by reducing the use of antibiotics in both medical and agricultural contexts.