Antibiotic-resistant bacteria discovered in clouds / Could rain become dangerous? Here’s what the researchers say

“These bacteria usually live on leaves or in the soil. We discovered that they were carried by the wind in the atmosphere and that they could travel long distances and even cross the globe at high altitude thanks to clouds,” said Florent Rossi, the study’s lead author, in during a telephone interview given to AFP on Friday.

To reach these conclusions, researchers from Université Laval in Quebec and Université Clermont Auvergne took samples of clouds forming over Puy de Dôme, a dormant volcano in central France, between September 2019 and October 2021. The clouds contained between 330 and over 30,000 bacteria per milliliter of water, for an average of approximately 8,000 bacteria per milliliter. Also, 29 subtypes of antibiotic resistance genes were identified in bacteria.

Considering the widespread use of antibiotics in the health system, but also in agriculture, this type of strain represents a “major challenge for health on a global scale”, the study indicates. On several occasions, world health authorities have emphasized the risks associated with these bacteria, which make the treatment of certain infections more and more complex.

However, the study provides no conclusions about the potential health effects of the airborne spread of bacteria carrying antibiotic resistance genes, estimating that only 5-50% of these organisms may be alive and potentially active.

Walks in the rain

“The atmosphere is very hard for bacteria, and most of those we found were environmental bacteria, less likely to be harmful to humans,” says Florent Rossi.

“We don’t have to fear anything when we walk in the rain,” said the researcher.