Clouds carry bacteria resistant to antibiotics – 04/29/2023 – Science

For a team of Canadian and French researchers, the dark clouds on the horizon are potentially threatening, and not because they signal the arrival of a storm. A study reveals that they transport drug-resistant bacteria over long distances.

“These bacteria usually live on the surface of vegetation, such as on leaves, or in the soil,” explained Florent Rossi, lead author of the study, in an interview with AFP on Friday (28). “We found that they are carried by the wind into the atmosphere and can travel long distances around the world, at high altitudes, in clouds.”

The finding was published in last month’s issue of the journal Science of The Total Environment. Researchers from Canada’s Laval University and France’s Clermont Auvergne University looked for antibiotic-resistant genes in bacteria found in cloud samples collected at an atmospheric research station located 1,465 m above sea level on top of France’s inactive Puy-de-Dôme volcano. , between September 2019 and October 2021.

An analysis of the recovered mist revealed that it contained between 330 and over 30,000 bacteria per milliliter of cloud water, with an average of about 8,000 bacteria per milliliter.

We also identified 29 subtypes of antibiotic-resistant genes in bacteria. Resistance occurs when bacteria are exposed to antibiotics and develop immunity to them over generations.

Health authorities have already warned that these adaptations are becoming what the study described as a “major health concern worldwide”, which makes it difficult and sometimes impossible to treat some bacterial infections, as the use of antibiotics continues to increase. in health and agriculture.

The study does not draw conclusions about the possible health effects of the spread of antibiotic-resistant bacteria, as it estimates that only 50% of these organisms could be alive and potentially active.

Rossi suggested that the stakes should be low. “The atmosphere is very stressful for bacteria, and most of what we found were environmental bacteria,” which are less likely to be harmful to humans, he explained. “People don’t need to be afraid to go out in the rain. It’s not clear whether these genes would be passed on to other bacteria.”

Atmospheric monitoring, however, could help pinpoint sources of drug-resistant bacteria, similar to testing wastewater for Covid-19 and other pathogens, “in order to limit their spread,” Rossi said.